Dilemmes et doutes - Centrale des maths

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Quel est le 6e nombre dans la serie suivante 2010-08-13

jeff pose la question :
Quel est le 6e nombre dans la serie suivante: 1,2,6,42,1806,...
Stephen La Rocque and Claude Tardif lui répond.

Deux nombres consécutifs 2010-01-18

Janot pose la question :
Bonjour comment peut on faire pour démontrer que si deux nombres sont consécutifs, leur produit et leur somme sont premiers entre eux Merci de me mettre sur la voie , j'ai échoué avec Bezout.
Claude Tardif lui répond.

Le plus grand commun diviseur 2009-11-11

Katie pose la question :
Question: Pendant mon cours de MAT 1300, mon enseignant m'a posé la question suivante:

(a, b) = 12
(a², b) = 24
(b, 72) = ?

Pouvez-vous m'aider s'il-vous-plaît?
Claude Tardif lui répond.

Le réservoir 2009-04-09

Myrianne pose la question :
Le réservoir d'essence d'une petite voiture peut contenir 50 litres. En sachant que 1 dm3 équivaut à litre, donne les dimensions de deux prismes différents représentant ce réservoir.
Claude Tardif lui répond.

Une série géométrique 2008-11-23

anass pose la question :
je vx savoire est ce kil existe la somme de (1/n^x) avec n variant de 0 jusk à infini
nota:
lorsk x=1et 2 la somme reste tjrs facile mé lorsquil depasse 3 c difficile et merci
Pierre-Louis Gagnon lui répond.

Logarithmique et semi logarithmique 2008-03-08

azaar pose la question :
Je veux savoir comment passer d'un échelle linière à l'échelle logarithmique ou semi logarithmique ?
Lierre-Louis Gagnon lui répond.

Le symbole ∈ epsilon 2007-10-10

Cora pose la question :
Je veux aider ma fille avec ses devoirs. C'est quoi le symbole qui semble un E, mais c'est un demi-circle? ie:X ∈ N
Claude Tardif lui répond.

addition et soustraction des heures, minutes, secondes 2006-11-22

Halnais pose la question :
13 h. 25 mn + 18 h. 06 mn
23 h. 31 mn + 19 h. 33 mn

je ne me souviens plus très bien de ces opérations, faut-il additioner les heures à part puis les minutes, etc. pour les heures je crois qu'il ne faut pas dépasser 24 h. Pourriez-vous m'aider, et me donner le résultat, merci infiniment.
Claude Tardif lui répond.

Des exercices complémentaires 2006-02-26

Nathalie pose la question :
Bonjour, mon fils est en 2e année dans une école de Montréal. Il éprouve des difficultés en mathématiques. Auriez-vous des sites à me suggérer dans lesquels je pourrait trouver des exercices complémentaires à lui faire faire.
Claude Tardif lui répond.

Inverse 2005-10-18

Pauline pose la question :
Défi ! a et b désignent deux nombres distincts non nuls. Peut-on trouver un nombre à retrancher du numérateur et du dénominateur du quotien a/b pour obtenir son inverse b/a?
Claude Tardif lui répond.

exercice! 2005-09-28

Un eleve pose la question :
soit x et y deux nomres réels telque:
1 ≤ x²-x*y+y² ≤ 2
1) Montrer que: 2/9 ≤ x⁴+y⁴ ≤ 8
2) Montrer que: x^2*n+y^2*n ≥ 2/3^2*n telque n est un nombre entier naturel et n≥3.
Chris Fisher lui répond.

quel sont les plus grands diviseurs communs? 2005-09-07

Sylvain pose la question :
quel sont les plus grands diviseurs communs?
Claude Tardif lui répond.

Opérations de base 2003-07-05

Anne-Marie pose la question :
Je m'appelle Anne-Marie et je suis enseignante de 5e année à l'école Domaine des copains de Balmoral au Nouveau-Brunswick. Récemment, j'ai participé à un concours intitulé: Budweiser King Pack Nascar Hat Promo. Afin de réclamer le prix, qui est une casquette, je devais répondre à une question réglementaire. Il s'agissait d'une phrase mathématique qui se présentait comme suit:

4 x 26 - 24 / 8 = qui se lit: 4 fois 26 moins 24 divisé
par 8
Claude Tardif lui répond.

La somme de 51 nombres entiers consécutifs est 1785 2003-04-01

Katrine et Armand pose la question :
La somme de 51 nombres entiers consécutifs est 1785, quels sont ces nombres? (indication : on rappelle que pour tout entier P, on a 1 + 2 + ....+ P = P (P + 1) / 2).
Claude Tardif et Penny Nom lui répond.

des conversions de bases différentes 2003-01-04

Christian pose la question :
Je cherche désespérément la (les) règle(s) pour réussir des conversions de bases différentes : de base x vers base y.
Claude Tardif lui répond.

La bissectrice de l'angle ABC 2000-02-16

Laurent Gauthier pose la question :
Est-ce redondant d'ecrire "angle ABC" avec un accent circonflexe sur le B? Peut-on ou devrait-on se contenter d'ecrire soit ABC (avec l'accent), soit l'angle ABC (sans accent) ? Le contexte dans lequel ceci apparait est le syntagme "la bissectrice de l'angle ABC", c'est-a-dire que je me demande si on devrait ecrire "la bissectrice ABC " (avec accent), "la bissectrice de l'angle ABC" (sans accent) ou "la bissectrice de l'angle ABC" (avec accent).
Claude Tardif lui répond.

Septante 1999-12-18

Guillaume Bessis pose la question :
Pourqoui et depuis quand en France emploie-t-on l'expression 'soixante-dix' et non septante pour désigner 70 ? (idem pour 90 et nonante)
Claude Tardif lui répond.

La longueur des segments formant un triangle 1999-10-05

Michel Provencher pose la question :
Connaissant la longueur des segments formant un triangle,comment détermine-t-on chacun de ses angles si:

il S'agit d'un triangle rectangle
Sachant que la somme des angles d'un triangle est de 180 degrés et sachant par conséquant qu'un des angle est de 90 degrés (triangle rectangle) il reste donc, 90 degrés à partager entre les 2 angles restant. Si les 2 segments formant l'angle droit sont de même longueur on obtient un angle de 45 degrés pour les angles restant soit 1/2 angle droit ce qui ne me pose évidement aucun problème. Quel relation, S'il y en a une, y a t-il entre la longueur de ces 2 segments et les angles restants.

il S'agit d'un triangle quelconque

Claude Tardif lui répond.

les fractions 1998-02-24

Colette Huguenin pose la question :
Bonjour je révise mes math de tout les secondaire et le livre louer la bibliothèque n'est pas entier voici le genre de problêmes qui me bloque
(5 4/5+1/2)divisé 1/3
je sais que je dois commencer par la parenthèse mais...je fait quoi comme opération avec le 5? dois-je le multiplier ou l'additionner ou.......????? si je pouvais seulement avoir la base des fractions je redébloquerais surement
Diane Hanson lui répond.

How to calculate percentage change 2007-08-03

Galland pose la question :
I am working on graphs and I need to find the percentage of increase from one figure to another. How do I do that? For instance staff hours for 2006 were 28011 and for 2007 were 31230. How do I find the percentage of increase?
Stephen La Rocque lui répond.

sec(pi/12) 2022-03-23

Diana pose la question :
Please help me find the exact value of the following trigonometric expression: sec(pi/12). Thanks!
Harley Weston lui répond.

An arithmetic and a geometric sequence 2021-08-29

Moti pose la question :
Let {an} be an arithmetic sequence such that its 1st, 20th, and 58th terms are consecutive terms of some geometric sequence. Find the common ratio of the geometric sequence.
Harley Weston lui répond.

Fibonacci numbers 2021-08-25

John pose la question :
Make a single column of numbers. Start with two numbers of your choice. The third number is the sum of the previous two, the fourth number is the sum of numbers two and three, and so on until you have ten numbers in the column. Add up all ten numbers. Now, take the seventh number and multiply it by eleven. This product will equal the sum of the ten numbers. The same result will occur regardless of the first two numbers chosen. The question is why does the 7th number multiplied by 11 always equal the sum of the ten numbers?
Penny Nom lui répond.

Division in different bases 2021-02-06

Promise pose la question :
Simplify the following 302 in base6 divided by 5 in base6
Penny Nom lui répond.

0^(a+bi) 2020-12-03

Douglas pose la question :
I realize raising 0^a = 0 if a>0 and undefined if a<=0.

If have read that 0^bi is undefined for all b.

What I don't understand is why 0^(a+bi) = 0 if a and b are not equal to zero.

Is this purely by definition or is there a logical reason why this is the case?
(I have taken Complex Analysis, so have a fairly good understanding of complex numbers.)
Penny Nom lui répond.

A problem involving distance, time, and rate. 2020-09-15

Ruby pose la question :
Amy drove on the highways at 70 miles/hour to pick up fruits from her grandma’s garden in the morning.
She stayed there for two hours. When coming back in the afternoon, she drove on the local roads at 40 miles per hour to avoid traffic.
She spent a total of 8 hours for this trip, and drove a total 300 miles.
How many miles did she drive each way?
Penny Nom lui répond.

Choosing 4 balls from 9 2020-07-22

sandiso pose la question :
What is the probability associated with each possible random sample of size 4 from the population consisting of these nine balls
Penny Nom lui répond.

Adding a service charge and the VAT 2020-04-30

richard pose la question :
was given a figure by a client been performance bonus of staff , the figure is 806,698.35 from this 806,698.35 is my company service charge of 10% and 5% of the service charge will be Vat to government in summary from 806,698.35 is 10% of service charge and 5% of service charge is the VAT
Penny Nom lui répond.

Building a house in one year 2020-04-22

Fify pose la question :
If it takes 8 men to build a house in 450 days. How many men would it take to build the house in 365 days? Is there a specific method to calculate this please?
Penny Nom lui répond.

An arch in the form of a semi-ellipse 2020-04-20

Anggelica pose la question :
an arch in the form of a semi-ellipse is 8 feet wide at the base and has a height of 4ft. how wide is the arch 1foot above the base?
Penny Nom lui répond.

Three consecutive odd integers 2020-04-10

Roxie pose la question :
What is three consecutive odd integers?
Penny Nom lui répond.

Setting up a linear equation 2020-04-10

Jessie pose la question :
Michaela and Aleah play on the same basketball team. In one game, Michaela scored one fifth of the teams points and Aleah scored one tenth of the teams points. Together, they scored a total of 42 points. How many points did the team score?

I can't figure out how to put together the equation with the given variables. I have to show the work and I also need to know how to make that kind of equation. Thanks!
Penny Nom lui répond.

An arithmetic sequence 2020-04-04

ally pose la question :
-10 ... last term 35 common difference is 3
(a) find the number of term in the sequence.
i have lost the formula.
Penny Nom lui répond.

A times table in base 5 2020-03-11

Felix pose la question :
Design a time table for numbers 1-10 in base 5
Penny Nom lui répond.

Degrees, minutes and seconds 2020-02-21

Jonathan pose la question :
If a cone has an angle of 22 degrees, when i place it flat on a surface, the new resulting central angle is now at 68.69123834, but how come when i saw it on my friend it say 68 degree and 40 minutes, what is this minute?
Penny Nom lui répond.

Multiplication base 8 2020-02-19

Tamesha pose la question :
Let’s count with the symbols 0,1,2,3,4,5,6,7 (base 8)
A). Create a multiplication table for this base
B). Compute the following products using the multiplication algorithm
I). 7605 times 3713
II). 63725 times 40627
Penny Nom lui répond.

Partitions of a set 2019-12-21

Ghani pose la question :
1. Are set partition "sets"?

2. If they are so then, why are both {{a}{b,c}} and {{a,b}{c}} said to be valid partitions
of A ={a,b,c} despite them having different elements?

(I understand that set are equal if they have the exact same elements).

Thank you!
Harley Weston lui répond.

Some questions about sets 2019-12-15

M.Azzi pose la question :
Hello, (I) - In set theory can a given set contain both elements and subsets, as "elements", as in : A = {1,2,{},3,{{3}},8}

If yes :
1 - then, is |A| = 6 ?
2 - if the empty set is a subset of every set,
2. 1. does {} = {{}}, {{{}}} etc? , and if the is true what are the respective cardinals of the latter three? (0,1,1?).
2 . 2. Why isn't {1} equal to {{},1}? and why should these two be equal without having the same cardinality?

Sorry if my questions are not well expressed.

Thank you for the great service you provide.
Harley Weston lui répond.

Combinations of cities 2019-12-03

Oliver pose la question :
Hi! I'm looking to find out how many combinations (non repeating) there are for 6 cities.
If we name the cities A to F, possible combinations would include;
A.
A, B.
B.
A, B, C.
A, C.
B, C.
C.

and so on.
Thank you!
Penny Nom lui répond.

Algebra 2019-11-06

Krizhia pose la question :
How is y= 1/2 * (x-1)² be x= √2y + 1. Please show me the steps
Penny Nom lui répond.

Increasing your average mark 2019-11-01

Elena pose la question :
After 9 weeks Mikayla has an average ark of 5 out of 10 in the weekly spelling tests. What is the minimum number of extra weeks now required to raise her average to 7?
Penny Nom lui répond.

The perimeter of a piece of a circle 2019-10-18

Arwin pose la question :
The radius of a circle is 17 cm. A chord XY lies 9 cm from the centre and divides the circle into two segments. Find the perimeter of the minor segment.
Penny Nom lui répond.

Four less than three times a number is 20 2019-09-29

Linda pose la question :
four less than three times a number is 20,what is the number?
Penny Nom lui répond.

The volume of a fire hose 2019-09-18

Carlou pose la question :
How many liters of water in a 2.5 inches diameter of fire hose with a 20 meters in length
Penny Nom lui répond.

The amount of concrete in a foundation 2019-09-11

Lorinda pose la question :
How do you calculate ( in cubic yards) how much concrete is needed for the foundation of a rectangular building 40 ft by 85 ft if the foundation walls are 8 inches thick and 7 ft 6 inches high?
Penny Nom lui répond.

What are the next three terms? 2019-06-18

Shriya pose la question :
-6, -2 , 2, 6,10 what are the next three terms?
Penny Nom lui répond.

Finite and infinite sets 2019-06-10

Pretzie pose la question :
What is Finite Set & Infinite Set?
Penny Nom lui répond.

(3d) Whether line segment intersects triangle 2019-04-13

rj pose la question :
Well hello,

Lets say I have a triangle,

Not any ordinary triangle, but a triangle that is represented in 3 dimensions. I also have a line segment.

Lets say that this triangle has points A(0,0,0), B(1,0,0), C(0,1,1)

And the line segment has points D(0,1/2,0), E(1,1/2,1)

In what way can I find if the line segment and triangle intersect? Their intersection point?

I don't prefer matrices, because they don't make any sense, but ... if that's the only way to solve this, then do what's necessary.

Thank you in advance.
Penny Nom lui répond.

4^x=2^x+6 2019-04-05

Olivia pose la question :
How do you find the (b,n) if the solution of the equation 4^x=2^x+6 can be expressed at logb(n) where b and n are both prime numbers?
Penny Nom lui répond.

Four consecutive positive integers 2019-03-12

Nabila pose la question :
The product of four consecutive positive integers in 24024
What is their sum?
Penny Nom lui répond.

Converting a base six number to base three 2019-03-10

Nina pose la question :
Change 253 in base 6 to a number in base 3
Penny Nom lui répond.

Misuse of greater than 2019-03-07

Kenneth pose la question :
I have an old business mathematics textbook. The authors have indicated that the following expressions indicate multiplication:

? is 2/3 greater than 90; ? is 2/3 smaller than 90. They also indicated that the following expression would indicate division: 30 is 2/3 greater than ? and 30 is 2/3 smaller than ?.

How can these phrases indicate multiplication and division? How can 60 be 2/3 greater than 90 and also smaller than 90 as indicated above. What were the authors thinking? I have added the page from the book that indicates what I have explained in my message Kenneth
Harley Weston lui répond.

Loan payment formula 2019-02-24

Kenneth pose la question :
I have a question regarding the loan payment formula shown below.

Calculating the Payment Amount per Period
The formula for calculating the payment amount is shown below.

Simple Amortization Calculation Formula

A = P X r(1 + r)n over (1 + r)n - 1

where

A = payment Amount per period

P = initial Principal (loan amount)
r = interest rate per period

n = total number of payments or periods

Is this formula/calculation a condensed version of a longer calculation? I am curious to know how the (1 +r)n - 1 was developed from the longer calculation. For example, r(1 + r)n may have been (r + rn)n. The n's are exponents.

I thank you for whatever helpful explanation that may be provided.

Kenneth

Harley Weston lui répond.

An arithmetic sequence 2019-02-23

Dalal pose la question :
If x+1 and -x+17 are the second and sixth term of a sequence with a common difference of 5, what's the value of x.
Penny Nom lui répond.

Margin with commission as part of selling price 2019-02-13

Anni pose la question :
I need to find selling price to put us at 24% margin.
15% commission is based on selling price and is included in our cost.
I'm trying to do it excel and keep getting a circular reference.
Total cost= cost + commission (15% of selling price)
Selling price=total cost + 24% margin
Penny Nom lui répond.

An arithmetic sequence 2019-01-31

sara pose la question :
if the 6th term of an arithmetic sequence is 8 and the 11th term is -2, what is the first term?
Penny Nom lui répond.

7 spheres on a hexagonal tray 2019-01-14

herm pose la question :
what is the length of each side of a hexagonal tray, with the height of each side 0.75 inch, to hold seven spheres, each with a diameter of 3.00 inches? The spheres are placed such that each side of the hexagon is touched by one sphere at its midpoint (and the seventh sphere is place in the center of the "ring" of the other six spheres.
Harley Weston lui répond.

Solve for x in Y=1.5x + log (1+x) 2018-12-23

Asadollah pose la question :
Please restate below expression in terms of y

Y=1.5x + log (1+x)

Thanks
Penny Nom lui répond.

Two cones formed from two circular sectors 2018-11-30

APARNA pose la question :
The central angles of two sector of a circle are 60° and 120° . Using these sectors two cones are made. If the radius of the smaller cone is 5 cm, find the radius and base area of the larger cone.
Penny Nom lui répond.

A line cuts a curve 2018-11-11

roxanne pose la question :
Hello, i need to ask a question, do you mind explaining and writing the formula of how to solve equations such as "find the set values of k for which the line y-2x-5 cuts the curve y=x^2 +kx+11" please
Penny Nom lui répond.

Why 1/2 in the area of a circular sector? 2018-10-26

Ariel pose la question :
In the equation for area of a sector=1/2r^2theta why is it 1/2? Please explain conceptually not algebraically.
Penny Nom lui répond.

Two curves 2018-09-23

Megan pose la question :
How do i find the interception points of xy=-2 and y=x+3? Many thanks!
Penny Nom lui répond.

A rotating wheel 2018-08-24

Kay pose la question :
A wheel with a radius of 7 inches is rotating at 4 revolutions per second. What is the linear speed v, in feet per second?
p lui répond.

Two intersecting tubes 2018-08-15

Tommy pose la question :
Hi, I am trying to determine a mathematical model for two metal tubes joining at various degrees for weld.
For instance, if I am trying to join the end of a tube to the side of another at a 90 degree angle, it will be a simple profile cut out of the joining tube.
Where it gets tricky is if you want to join the new tube at a given angle.
It would be very helpful if you could give insight as to how I can solve this problem or an equation I could work off of.
Thanks for the help!!
Edward Doolittle lui répond.

Form a cone from a circle sector 2018-08-12

Tinashe pose la question :
A 216 sector of a circle of radius 5cm is bent to form a cone. Find the radius of the base of the cone and its vertical angle.
Penny Nom lui répond.

Creating a number sentence 2018-06-29

trish pose la question :
First I have to solve the problem. Then write a number sentence for the problem. The problem: By installing a $120.00 thermostat that reduces the temperature setting at night a family hopes to cut its annual fuel bill for heating oil by 8%, and recover the cost of the thermostat in fuel savings after 2years. What was the family's annual fuel bill before installing the thermostat? Thanks can't figure this one out!
Penny Nom lui répond.

Soil in a raised bed 2018-06-24

Georgia pose la question :
Good Afternoon,

I'm planning on building a raised bed garden measuring 6 feet long x 4 feet wide x 12 inches deep. I'm not sure how to calculate the amount of soil to fill it up. I will have to purchase the soil in 2 cubic feet bags.

I've read several articles about this topic on various gardening websites, and one of them stated it would take a ton of soil to fill up an 8 foot long x 4 foot wide x 12 inch deep raised bed garden.

I'd greatly appreciate it if you could help me out with this quandary.

Thank you for your prompt and courteous response.

Kind Regards,
Georgia
Penny Nom lui répond.

Three consecutive whole numbers 2018-06-22

whaha pose la question :
the sum of three consecutive whole numbers divided by 4 is equal to 6. find the numbers.
Penny Nom lui répond.

A question about the empty set 2018-06-17

Andrey pose la question :
Hello there!
I got that an empty set is a subset of every set.
There is a question.
Is an empty set an element of every set?
∅ ⊆ {x}True
∅ ∈{x}?
Sorry if the question is easy. A set theory is a bit confusing.
Penny Nom lui répond.

The number of terms in an arithmetic sequence 2018-06-15

Don pose la question :
how many terms in arithmetic sequence are there if the first term and the last term are 3&59 respectively in common difference is 4?
Harley Weston lui répond.

The base for a circular pool 2018-06-10

Adam pose la question :
How many sheet of 4ft by 8ft foam would I need to lay under a pool 15dt in diameter
Penny Nom lui répond.

The inverse square law 2018-06-05

Amy pose la question :
Question about inverse square law ;

Hi, I'm trying to understand some nuances about this law and
have been reading about it a lot online and trying out some homework
for personal interest (hobby ) - not school related.

I understand that the simple formula is ; 1/d^2

I was wondering about what appears to be an oddity to me, that
I came across when I was working with a test example I found at this
link ;

http://www.softschools.com/formulas/physics/inverse_square_law_formula/82/

The problem that caught my interest was this one on that page ;

"1) If a bright flashlight has a light intensity of 15.0 candela at a distance 1.00 m from the lens, what is the intensity of the flashlight 100.0 m from the lens?"

So I have a few different questions about this, but the most important
one is, what does it mean if we replace the "1" in ; 1/d^2 with a different value such as a ratio in the form of a decimal value, so instead we have something like this ;

0.75/d^2

???

Does this ratio represent a curve then?

I am thinking that the "1" in the normal formula represents a straight line

Some of the links I was researching ;

http://wisptools.net/book.php?c=3&s=2

http://www.softschools.com/formulas/physics/inverse_square_law_formula/82/

https://www.nde-ed.org/GeneralResources/Formula/RTFormula/InverseSquare/InverseSquareLaw.htm

Penny Nom lui répond.

Two odd integers 2018-06-04

Pleroma pose la question :
The product of two alternate odd integers exceeds three times the smaller number by 12. What is the larger number?
Penny Nom lui répond.

What is the diameter of the observable universe? 2018-05-27

peter pose la question :
The diameter of the observable universe is calculated to be 92 billion light years. What would that distance be in miles given a light year is 6 trillion miles?
Penny Nom lui répond.

Gauss' Addition of whole numbers. 2018-04-30

Brad pose la question :
I found this on your site. Question: what is the sum of the first 100 whole numbers?? Is there a different formula if the numbers begin at a number other than one? For example What is the series I want to add is goes from 7 - 53?
Harley Weston lui répond.

Seven tangent circles 2018-04-23

Domenick pose la question :
How to calculate the circumscribed and inscribed circles formed by seven .019685 diameter circles arranged in a circle with all seven circles tangent to each other?
Penny Nom lui répond.

Base 6 to base 4 2018-03-25

Malik pose la question :
Hi Sir..!
I just want to know the proper example with a brief explanation of conversion of base 6 into base 4. kindly reply me as soon as possible.. Thank you
Penny Nom lui répond.

Walking a fraction of a mile 2018-03-20

Jamie pose la question :
Who walked a fraction of a mile that is closer to neither 0 nor 1 ? Explain
Avery 1/6
me.Nunez 5/6
Ms. Chang 1/3
Mr. O’Leary 4/8
Miss Lee 4/6
penny Nom lui répond.

A geometric series 2018-03-13

nathi pose la question :
Hi I am really struggling with this question please help !!!!
a pohutukawa tree is 86 centimetres when it is planted. in the first year after it is planted , the tree grows 42 centimetres in height.Each year the tree grows in height by 95% of the growth of the previous year.
assume that the growth in height of the pohutukawa tree can be modelled by a geometric sequence.
A)find the height of the tree 5 years after it is planted and figure out the maximum height the pohutukawa tree is expected to reach in centimetres. The maximum height part is not answered.
Penny Nom lui répond.

The intersection of a curve and a line 2018-03-08

lola pose la question :
find the set of values of constant C for which the line y=x+c intersects the curve y=2 square root x at, at two distinct points
Penny Nom lui répond.

nC0 + nC1 + nC2 + .... + nCn = 2^n 2018-02-19

bristal pose la question :
(QQ) Prove, nC0 + nC1 + nC2 + .... + nCn = 2^n.
Penny Nom lui répond.

A puzzling sequence 2017-12-19

Alan pose la question :
My son has the following sequence to work out the formula for the nth term (and fing 5th and 6th terms) and I have tried a variety of ways but can't help!

1/2, 5/6, 1, 11/10

I have converted all to 15/30, 25/30, 30/30, 33/30 and so think the next two terms are 37/30 and 45/30 but I have no idea how to prove or if I am right!

Any help appreciated.
Penny Nom lui répond.

An arithmetic sequence 2017-11-30

yo pose la question :
x; 2x+1; 11 are three consecutive terms of an arithmetic sequence.calculate x
Penny Nom lui répond.

Sampling distribution 2017-10-16

Esther pose la question :
I need 4digits combination of 235689 and without replacement. Thanks
Penny Nom lui répond.

Three consecutive odd integers 2017-10-10

Johanna pose la question :
Three consecutive odd integers are such that the sum of the first and second is 31 less than 3 times the third
Penny Nom lui répond.

Four multiples of 10 2017-09-23

Laudacir pose la question :
Four multiples of 10 are added together.the total is a 3 digit number with three consecutive digits. What could the four number be?
Penny Nom lui répond.

An alphabetic sequence 2017-09-17

malik pose la question :
find the letter of the following series....?

ZOTTFFSSE-
Penny Nom lui répond.

A rope formed in a semicircle 2017-08-29

Janna pose la question :
How do I find the total length of a piece of rope formed in a semicircle that has a diameter of 8 inches?
Penny Nom lui répond.

Two circles 2017-08-13

Ladines pose la question :
Find the equation of the circle passing through points of intersections of circles x²+y²=4y and x²+y²=2x and the center is on line y=2
Penny Nom lui répond.

The perimeter of a sector of a circle 2017-08-11

Alisa pose la question :
find the perimeter of the sector with radius 7 cm in which the angle at the centre is 60 degrees leave your answer in terms of pi
Penny Nom lui répond.

A semi ellipse 2017-07-25

Ian pose la question :
The arch of the bridge is in the shape of semi ellipse,with its major axis at the water level.suppose the arch is 20ft. High in the middle,and 120 ft. Across its major axis. How high above the water level is the arch,at a point 20 ft.from the center (horizontally). Round of 2 decimal places
Penny Nom lui répond.

3 consecutive multiples of 11 2017-07-22

nisha pose la question :
using the multiples formula shown at ypur site how can we solve finding 3 consecutive multiples of 11 whose sum is 363
Penny Nom lui répond.

An arithmetic sequence 2017-07-17

abbi pose la question :
hi there im a student in 11 grade

ive been trying to do this task but i have no idea how to do it the question is
Find the common difference and the n^th term of the arithmetic sequence if the first term is 4 and the twentieth sum of the terms is 1030
Penny Nom lui répond.

Two consecutive odd integers 2017-07-14

Adeeb pose la question :
Find two consecutive odd positive integers, sum of whose square is 290.
Penny Nom lui répond.

Three consecutive natural numbers 2017-06-11

Anita pose la question :
Three consecutive natural numbers are such that the square of the middle number exceeds the difference of the square of the other two by 60. Find the numbers.
Penny Nom lui répond.

Two wires between two buildings 2017-05-11

Bill pose la question :
I need to find the height of the intersection point of two building wires< br /> Building A is 860 feet high and building B is 480 feet high. The wires existent from the top of one building to The bottom of the other < br /> The distance between is 32 feet
Penny Nom lui répond.

Yards per second to miles per hour 2017-05-11

Scott pose la question :
If a soccer ball travels 30 yards or roughly .017 miles in 2 seconds how fast was the ball going in mph?
Penny Nom lui répond.

Selling price and markup 2017-04-24

Julie pose la question :
What would the cost of an item be, if the sell price was $50 and the markup 48%
Penny Nom lui répond.

Baseball Cards 2017-04-20

Raquel pose la question :
A minor league baseball team gave away baseball cards to each person entering the stadium. One group receives 28 baseball cards. A second group received 68 baseball card. If each person entering the stadium receive the same number of cards, what was the greatest possible number of baseball cards that each person could have received?
Penny Nom lui répond.

A function which is onto but not one-to-one 2017-04-16

Avinash pose la question :
Define a function f(x):N-->N which is onto but not one-one.Where N is set of natural numbers.
Penny Nom lui répond.

Forming a cone from a circle 2017-04-15

Tasha pose la question :
A sector of a circle subtends an angle of 216 degrees at the centre, If this sector is used to form a cone of vertical height ,8cm, calculate the base radius of the cone
Penny Nom lui répond.

Successive Differences 2017-04-06

Twaha pose la question :
Please find the equation of the sequence 1 2 4 7 11 16 22
Penny Nom lui répond.

Faster than as a percentage 2017-03-18

Maximilian pose la question :
Hi, i have a strange issue with the phrase "faster than" in percentage, ie. if i have a 10MB/s connection, and somebody has a 7MB/s connection, is it 30% faster or 50% faster.- which ( affirmation, phrase, sentence ) is the right one:

a:) My 10MB/S connection is 50% faster than the 7MB/s ?
or
b:) My 10MB/S connection is 30% faster than the 7MB/s ?

Thanks in Advance, and please if you can teach me why !
Penny Nom lui répond.

A block base for a plywood rectangle 2017-02-18

Joe pose la question :
How many cinder blocks 16x8 would i need to build a solid base for a plywood base 54inches wide and 30 inches deep Thank you
Penny Nom lui répond.

Addition and subtraction base 5 2017-01-29

BABAWALE pose la question :
Simplify 342five +132five-223five
Penny Nom lui répond.

Feet per second to miles per hour 2017-01-27

ron pose la question :
if a vehicle travels 50 feet in 2.5 seconds what is the speed in mph. 3600 sec in hour /5280 feet in a mile i get .68181818. how do i figure the 2.5 seconds. all the calculators I've used show 34 mph is that correct or am i forgetting the 2.5 second. please help.
Penny Nom lui répond.

The volume of a slab 2017-01-21

Russell pose la question :
Working with a segment of a circle. The O.D. is 3.440" the length of the chord is 3.130 I need information on the volume of the largest area. I would like to know (in thousands of an inch) how tall would the largest area need to be to equal .1143 cubic inches If you need more info I can send it Thanks in advance
p lui répond.

The inverse of y=x^2+x+c 2016-12-21

Sam pose la question :
What is the inverse of y=x^2+x+c for x?
Penny Nom lui répond.

The inverse of y = x(x - 2) 2016-12-21

Sasha pose la question :
Hello, I recently stumbled upon this question and I haven't been able to figure it out.

Why is the inverse of y=x(x-2) not a function?

Suggest a domain restriction which would ensure that the inverse is a function.

Thank You :)
Penny Nom lui répond.

4444 base five 2016-11-11

John pose la question :
If 4444 is a number in Base5, is 624 its value?
Penny Nom lui répond.

A pattern rule for a sequence 2016-10-28

Grace pose la question :
Here's a Grade 7 question, we need to find the pattern rule:

1 - 1
2 - 3
3 - 6
4 - 10
......
It may involve exponents, but we can't seem to figure it out.
thank you.
Grace.
Penny Nom lui répond.

The derivative of the inverse of a function 2016-10-28

Kate pose la question :
Hi, I'm in a College level Calculus course and I can't seem to figure out the answer to this question.
Find the derivative of f^-1(4) if f(3)=4 and f'(3)=1/7
Penny Nom lui répond.

Subtraction of two numbers in different bases 2016-10-07

Wica pose la question :
Hello,

So happy I found this site. I am having problems with bases. My question is :
Please perform the subtraction between two number over different bases :
A. (5874)base 12 - (216)base 9
B. (216)base 9 - (5874)base 12
Penny Nom lui répond.

A kinky curve 2016-10-06

tammie pose la question :
Koch’s kinky curve is created by starting with a straight segment and replacing it with four segments, each 1/3 as long as the original segment. So, at the second stage the curve has three bends. At the next stage, each segment is replaced by four segments, and so on. How many bends does the curve have at the third stage?
Penny Nom lui répond.

A car chase 2016-09-25

Ms. pose la question :
Car 1 is traveling down the road at 50 mph and passes Car 2 is sitting on the side of the road. Car 2 needs to catch Car 1 one half mile down the road. How fast must Car 2 drive to catch Car 1 if Car 2 waits 10 seconds before pursuing Car 1?

Yes, the assumption is that the Car 2 can accelerate from a standing position and over take Car 1 rate. What is the answer or formula for this type of question?
Respectfully
Befuddled Mom?
Penny Nom lui répond.

How fast and how far must Car 2 travel before catching Car 1? 2016-09-25

Ms. pose la question :
Car 1 is traveling down the road at 50 mph and passes Car 2 is sitting on the side of the road. Car 2 needs to catch Car 1 one half mile down the road. How fast must Car 2 drive to catch Car 1 if Car 2 waits 10 seconds before pursuing Car 1?

Yes, the assumption is that the Car 2 can accelerate from a standing position and over take Car 1 rate. What is the answer or formula for this type of question?
Respectfully
Befuddled Mom?
Penny Nom lui répond.

The distance around a warehouse 2016-09-21

Chuck pose la question :
How far do I walk when I walk around a 751,000 sq. ft. warehouse?
Penny Nom lui répond.

Two sequences 2016-08-20

Ting pose la question :
The first four terms of a sequence are 4, 20, 56 and 120. By comparing with the nth term of sequence 1,5,14 and 30 which is 1/6n(n+1)(2n+1), find a formula for nth term. Can you precisely show out how you do this questions ( with the steps please)
Penny Nom lui répond.

A search area 2016-08-13

tammy pose la question :
if your searching an area and you go 300 km from point A and search 380° what or how much area would you search?
Penny Nom lui répond.

Five consecutive even integers 2016-08-12

Marcelle pose la question :
The average of 5 even consecutive numbers is 112. What is the largest numbers?
Penny Nom lui répond.

The sequence 13 17 23 27 33 37 2016-07-29

Shriya pose la question :
The first term of a sequence is 13.
The following terms are found by alternately adding 4 and 6 to the previous term. The first six terms are 13 17 23 27 33 37.
Find the 80th term.
Penny Nom lui répond.

Which term of this sequence has value 8? 2016-07-20

Lauren pose la question :
Hi there

Which term in the sequence -2; -5/3; -4/3 ; -1; ... has a value of 8.

Since term 2 and 3 of this sequence contain fractions which can be converted to recurring decimals. What is the best way to work out the common difference here.

I do however understand that to work out the nth term of an arithmetic series, the following formula Tn = a + (n-1)d. In this series a = -2
Penny Nom lui répond.

Subsets 2016-06-26

Kats pose la question :
How Many sub sets are in set k={6,7,3}
Penny Nom lui répond.

The inverse function for f(x)=2x^2+5x 2016-04-23

Ashini pose la question :
The inverse function for f(x)=2x^2+5x
Penny Nom lui répond.

A sector of a circle 2016-04-21

mustafa pose la question :
In a sector of a circle, the arc length is equal to half the perimeter of a sector.find the area of a sector in terms of r
Penny Nom lui répond.

A road trip word problem 2016-04-10

Marc pose la question :
While on a road trip I imagined this random word problem. Suppose I start a trip of 75 miles. My initial speed is 75 miles per hour. After every mile traveled I decrease my speed by one mile per hour. After the first mile I decrease my speed to 74 miles per hour and so on for each subsequent mile traveled. How long will it take to complete the 75 mile journey?
Penny Nom lui répond.

Setting up a pool 2016-04-09

BETH pose la question :
i am trying to cover an area for a 15x15 foot round pool with play sand before I set up the pool. My playsand bag is 50 lbs , says it covers .5 cubic feet per bag. How many bags do I need?
Penny Nom lui répond.

A square based box and a cylinder 2016-03-26

rajpal pose la question :
i m trying to calculate an area required to hold 4.4 mln cubic metres of volume. I used square and I get below result

A box shape that has dimensions 1500 meters (1.5km) by 1500 meters (1.5km) by 2 meters depth has a volume of:
= 4,500,000 cubic meters (4.5 mln cubic meters)

but when I use a cylinder shape, i get below result

A cylindrical shape that has a radius of 850 meters and a depth of 2 meters has a volume of:
= 4,539,600 cubic meters (4.54 mln cubic meters approx)

why is it that the cylinder, though of same depth holds more volume than a square? kindly clarify.
Penny Nom lui répond.

A problem in base x 2016-03-25

Malith pose la question :
determine the value of base x of (211)x = (152)8

please mentioned the steps
Thank you
Penny Nom lui répond.

The inverse of a function 2016-03-20

Billy pose la question :
f(x) = Square root(x^2 + 2x)

What is the inverse?
Penny Nom lui répond.

tan inverse 1/4 2016-03-14

nazz pose la question :
prove; tan inverse 1/4=1/3 cot inverse 52/47
Chris Fisher lui répond.

Can you construct a regular 21-gon? 2016-03-08

Peter pose la question :
hi, i know that if i use a compass to draw a circle, i can use the same setting to mark 6 intervals along the circle circumference, how would i go about marking out 21 equally spaced points around the circumference?

if there an online calculator i can us, or some other interesting trick?

tia

peter
Robert Dawson lui répond.

A geometric progression 2016-03-03

Pauline pose la question :
A woman measures the height of her child at birth and at monthly intervals afterwards.The child's height increases by 5% per month. Find the number of measurements she has made before the child's height is twice what it was at birth
Penny Nom lui répond.

Compressed Earth blocks 2016-03-02

John pose la question :
how many 14"x10"x4" blocks do I need for a 1300sq foot house 8 foot high
Penny Nom lui répond.

A deck that is half an ellipse 2016-02-28

Steve pose la question :
On your website, I was reading a question and your response from a girl named Angela in which you provided a formula by which her father, a welder, could figure out points on an arc corresponding to equal 3' intervals on a 30' chord where the vertex was 1' off the chord. Is there an equivalent formula when working with an ellipse? I suspect this change will make the calculations significantly more complex. I am building a deck that is half an oval, and would like to be able to mark out the perimeter by measuring the distance from regular intervals on the primary access to a corresponding point on the perimeter. I will then connect the points on the perimeter and cut a reasonably smooth arc. The length of the primary access will be 22' and width of the deck at the vertex is 9'. I would like to be able to know the distance from the primary axis to a point on the perimeter at equal intervals of 6" along the primary axis. Can you help?
Penny Nom lui répond.

Division base 5 2016-02-01

Jenalee pose la question :
I am having problems with a dividing bases question. I reviewed two that I could find in the database and tried the question as shown but I am still getting the wrong answer.

My question is 32\24043 to the base of 5 for both.
Penny Nom lui répond.

Which term of the series 2+7+12+...is 152? 2016-02-01

francis pose la question :
whice term of the series 2+7+12+...is 152?
Penny Nom lui répond.

Subtraction in a base larger than ten 2016-01-31

Jenalee pose la question :
Hello,

So happy I found this site. I am having problems with bases. My question is 97B9 - 6A3A base 16 for both.

Please help.
Penny Nom lui répond.

Percentage reduction 2016-01-30

Kuuku pose la question :
The daily production targets in 2000 was 60,000 units this declined to 48,000 units in 2001 but was projected that further 300units reduction would be experienced in 2002. Calculate the percentage reduction by 2002.
Penny Nom lui répond.

Consecutive angles of a parallelogram 2016-01-28

Hanna pose la question :
The consecutive angles of a parallelogram measures
Penny Nom lui répond.

Two increases of 20% 2016-01-27

Z pose la question :
How do I find how many books are in a library given a problem like this... The number of books increase after buying 20% more in May. The number increased again by 20% after they were given 300 books. How many books did it start with?.
Penny Nom lui répond.

Two increases of 20% 2016-01-27

Z pose la question :
How do I find how many books are in a library given a problem like this... The number of books increase after buying 20% more in May. The number increased again by 20% after they were given 300 books. How many books did it start with?.
Penny Nom lui répond.

I was paid 67% of the total owed 2016-01-25

Julie pose la question :
I was paid $27000. This is 67% of the Total Owed. The Total Owed is unknown. How do I calculate the amount of the Total Owed?
Penny Nom lui répond.

Countable and uncountable sets? 2016-01-15

wilson pose la question :
what are the countable and uncountable sets?
Penny Nom lui répond.

The range of a function defined piecewise 2016-01-13

sarah pose la question :
f(x)={x-2, x<-2
       {x^2-4, -2_<x_<2
       {x+2, x>2

find the range
Penny Nom lui répond.

Three consecutive integers 2016-01-07

ronn pose la question :
Three consecutive integers whose sum is 186
Penny Nom lui répond.

A sequence 2016-01-05

Mia pose la question :
the next three terms in each sequence. 0.4, 0.54, 0.68, 0.82,
Penny Nom lui répond.

Four consecutive integers 2016-01-05

sherica pose la question :
my teacher gave us an assignment and it says here that; THERE ARE FOUR CONSECUTIVE INTEGERS.IF THE SMALLEST ONE IS x ,FIND THE SUM OF THE FOUR INTEGERS. that is the question ...thanks hope that u can answer it
Penny Nom lui répond.

Book sales 2015-12-30

Sandra pose la question :
Your finance text book sold 56,500 copies in its first year. The publishing company expects the sales to grow at a rate of 20.0 percent for the next three years, and by 8.0 percent in the fourth year. Calculate the total number of copies that the publisher expects to sell in year 3 and 4.
Penny Nom lui répond.

Proof that an erroneous algebraic statement is false 2015-12-14

Berteanu pose la question :
I need help with this proposition:
"It exists x a real number that for every y real number 5*x-2*y*y=1
This is false.
Let x be from R.
And I need an y real number that 5*x-2*y*y!=1
Please,could you help me?
Penny Nom lui répond.

The line of intersection of two planes 2015-12-09

Rabz pose la question :
Determine the vector equation for the intersection between the two given planes 2x+7y equal to 14,x+z equal to 7
Penny Nom lui répond.

Roof Square footage 2015-11-11

Todd pose la question :
Question from Todd:

Good Day.
I have to figure out the square footage of a quonset style roof that's not playing by the rules The building dimensions (rectangular) are 63'x135' the height of the roof is 9.25'. It not an entire Quonset, It's that style of roof,(curved). There are concrete block walls 10' up to the metal roof.

Thank you!

Todd

Harley Weston lui répond.

Subtraction in base 8 2015-10-21

Adi pose la question :
Hi! Can you help me with a nagging problem, I searched a lot over the web and couldn't find it. I saw this site I gave it a try and I found it to my liking.

I am confused how to subtract bases from other bases:
567 (in base 8)
- 456 (in base 8)
______________
?????????
How do you do this? I do know how to carry and subtract with different bases. Can you please help me?

Thanks,
Adi
Penny Nom lui répond.

The sequence 1,2,4,7,11,16... 2015-10-15

HEMANT pose la question :
what is the next term in the sequence : 1,2,4,7,11,16,?
Penny Nom lui répond.

Seven switches with 3 stages each 2015-09-15

jeff pose la question :
We are trying to solve a combination problem. If I have 7 things that can be in 3 states (say on/partially on/off), and all 7 have to a state. How many different combinations can there be? It doesn't seem like we should treat it as 21 independent things, but not sure how to break the problem apart.
Penny Nom lui répond.

Subtraction base 5 2015-08-29

nakita pose la question :
can u explain the quinary subtraction ...
(3000) -(2342) all the numbers are in quinary number system
Penny Nom lui répond.

The distance over a Quonset 2015-08-20

jane pose la question :
total base of hemisphere is 30 ft apex height is 20 feet what is total length over dome
Penny Nom lui répond.

The nth term 2015-07-04

ujjal pose la question :
What is the nth term in the order 6,8,10....
Penny Nom lui répond.

Why is the area of square not conserved when it changes to a rhombus? 2015-06-28

shubham pose la question :
Why is the area of square not conserved when it changes to a rhombus, both have equal sides still rhombus have less area than square.??
Penny Nom lui répond.

The intersection of a plane and a cone 2015-05-16

Tom pose la question :
Is there a way to derive an equation that describes the perimeter of the intersection of a plane and a cone regardless of the angle of the plane to the cone. Assume that the plane does not cut through the base of the cone, the x, y, z location of the vertex is known, the distance from the vertex to the plane through the axis is know., and that the angle of the cone is known.
Chris Fisher lui répond.

The number of possible musical notes using an n-key instrument 2015-05-04

Farihin pose la question :
Lets say that i have keys, and each key is for notes of a musical instrument, So i wanted to find out the number of notes i can get for a certain number keys, of course in the form of an equation. Notes can use as many keys, it can use 1, or 2, or 3, or even 100.
Notes in real life is not as such, but ignore reality. I tried doing this but i can't seem to find a formula for it. For example, i have 4 keys, say A, B, C, and D. so, for notes that uses one key are 4, which is A, B, C, and D themselves. for notes that uses two keys are 6,
AB, AC, AD, BC, BD and CD.
for notes that uses three keys are 4,
ABC, ABD, ACD and BCD.
lastly for notes that uses all four keys is 1, ABCD.
So, the total will be 4+6+4+1=15#

The nth term for the first equation is n, the second is [(n^2)-n]/2 the third and the fourth, i don't know but the final answer should be like,
n + [(n^2)-n]/2 + [3rd] + [4th]

Sorry for the long question though...
Penny Nom lui répond.

A piecewise function 2015-04-25

uday pose la question :
f(x)={x^2+3x+2 / x+2, x(not equal to)=-1
{4, x=-1
how to find domain and how the graph looks like

Penny Nom lui répond.

A geometric sequence 2015-04-19

Delfina pose la question :
In a geometric sequence the second term is 15 and the fifth term is -405. Find the sum of the first eight terms
Penny Nom lui répond.

Team selection 2015-04-13

Peter pose la question :
I manage a football team with a list of 28 players.
Only 24 can play each game.
The season is 16 games.
How do I fairly select 24 players each week.
Robert Dawson lui répond.

Some non-decreasing sequences 2015-04-13

Sky pose la question :
Hi I'm a Student and i'll try my best to state the problem perfectly.

The number of non-decreasing sequences of size at least 1 and at most N, such that each element of the sequence lies between L and R, both inclusive.

Eg:- N=1 L=4 R=5
ans= 2. [{4},{5}]

N=3 L=4 R=6
ans= 19. [{4},{5},{6},{4,4},{4,5},{4,6},{5,5},{5,6},{6,6} {4,4,4},{4,4,5},{4,4,6},{4,5,5},{4,5,6},{4,6,6},{5,5,5},{5,5,6},{5,6,6} ,{6,6,6}]
Claude Tardif lui répond.

Excavating a basement 2015-04-12

Randy pose la question :
The cost of excavation is $4.50/ cu yd. Find the cost of excavating a basement 87 ft long, 42 ft wide, and 8 ft deep.
Penny Nom lui répond.

A tangent to y=x^3 passes through (0,2) 2015-04-05

Kevin pose la question :
Given that the curve y=x^3 has a tangent line that passes through point (0,2). Find the equation of the tangent line
Penny Nom lui répond.

Three consecutive integers 2015-03-28

Aleksey pose la question :
I need help how do I find the second of three consecutive integers if the sum of the first and third is 26?
Penny Nom lui répond.

Two consecutive odd integers 2015-03-09

gowtham pose la question :
The sum of two consecutive odd integers is 20.find the integers
Penny Nom lui répond.

Integers in different bases 2015-03-05

Michael pose la question :
Let k be a positive integer so that 28 (subscript)k = 132 (subscript)5
Penny Nom lui répond.

Two consecutive positive integers 2015-03-01

meha pose la question :
Find two consecutive positive integers , sum of whose squares is 365.
Penny Nom lui répond.

Solve x=r(t-sin(t)) for t 2015-02-28

David pose la question :
I don't know how to write the function of t(x) by x=r(t-sin(t)).
Can you teach me that?
Harley Weston lui répond.

A question in set theory 2015-02-25

Jared pose la question :
If a set A={1,2,3} and set B={ {}, 1}

Can B be a subset of A? Since every Set contains an {} ?
Robert Dawson and Claude Tardif lui répond.

A stone is dropped in a lake 2015-02-14

Wendy pose la question :
Hi, I have problems solving this problem. We didn't exactly go over these kind of problems and the book doesn't have an example either. Thank you for your help!

A stone is dropped in a lake, creating a circular ripple that travels outward at a speed of 80 cm/s.
(a) Find a function g that models the radius as a function of time t.

g(t) =

(b) Find a function f that models the area of the circle as a function of the radius r.

f(r) =

(c) Find f compose g.
f compose g =

Penny Nom lui répond.

What is our cost? 2015-01-27

Johanna pose la question :
I have a pieces of 3/4" sch40 (round tube) 240" long at $70. What is our cost. We also add 35% to our cost for selling price. How do I figure this out?
Penny Nom lui répond.

Math in the universe 2015-01-21

GA pose la question :
I want to find out examples in universe for this equation:
sin(x)/cos(x)=1 or tan(x)=1. I know the mathematical answer of pie/4 or 45 degree angle.

What I need to know is to find examples of this. I found an example in construction, for example, which is the shape of attic in the house.

I want to find examples in universe like in solar system, in quasars or jets coming out of them, in galaxies, in stars, in black holes, etc

Do you know of any such examples?
Robert Dawson lui répond.

1,4,9,61,52,___ 2015-01-21

Mubashir pose la question :
1,4,9,61,,52,___,84,___,18,1,121,___ please tell me its formula and also that rule that is being applied here like adding 3 or subtracting 5 etc.
Walter Whiteley lui répond.

A sequence 2015-01-13

cyaz pose la question :
write a rule for each sequence then find next 3 terms for 7/8, 3 1/8, 5 3/8
Penny Nom lui répond.

211basex=152base8 2014-12-15

Humaira pose la question :
211basex=152base8
Penny Nom lui répond.

A line segment of length root 5 2014-12-15

angela pose la question :
On the dot grid below, draw and label a line segment with length square root 5 the dot grid is 8 by 10
Penny Nom lui répond.

A truncated, square-based pyramid 2014-11-23

Hannah pose la question :
A designer vase has the shape of a truncated, square-based pyramid. The base of the vase is a square with a side length of 15 cm. The area of the square opening is 70.56 cm2. Each of the four sides is a trapezium with slant sides 9 cm long. Find (to the nearest square centimetre) the total surface area of the vase.
Penny Nom lui répond.

Factorise 15x + 15y 2014-11-20

Jordan pose la question :
hi i saw a question in class today that i didn't understand and i didn't really understand what my teacher was going on about so how do you factorise 15x + 15y
Robert Dawson and Penny Nom lui répond.

The density of sea sand 2014-11-02

Lenny pose la question :
Hi There,

I need to find out the the density of sea sand to convert one metric ton to cubic meter as I am submitting for a tender which is in cubic meter but the requirement is in metric ton. I searched through the web site but no density of sea sand is given though there is specific Gravity of dry sand is available. I was given a density of 1.6 to work with. If that is true am I right to say that 1 cubic meter of sea sand is equivalent to 1.6 metric ton? Please help as I am getting confused with what I am able to find out on the web.
Thanks much in advance
Rgds
Lenny
Penny Nom lui répond.

logbase4 (sin x) = -0.5 2014-10-26

Susan pose la question :
Solve for x: logbase4 (sin x) = -0.5
Penny Nom lui répond.

Find the nth term 2014-10-26

Kenneth pose la question :
According to the pattern of the following sequence. Find it's nth term: 3,9,27,81,243,..........
Penny Nom lui répond.

A truncated square-based pyramid 2014-10-22

Beth pose la question :
How do you find the height of the original square-based pyramid when given the sides (12cm) of the base and height (6cm) of the truncated pyramid, as well as the sides (3cm) of the base of the chopped off top (chopped off parallel to the base)?
Penny Nom lui répond.

Three consecutive odd integers 2014-10-17

Maddy pose la question :
3 times the largest of three consecutive odd integers is 13 more than the sum of the other two. What are the integers?
Penny Nom lui répond.

Division in base 3 2014-09-30

Nnubia pose la question :
1021 in base 3 divided by 2 in base 3
Penny Nom lui répond.

Continuity on a closed interval 2014-09-21

Pragya pose la question :
The trouble I'm having is as follows :
a continuous function is most of the times defined on a closed interval, but how is it possible to define it on a closed interval ,because to be continuous at endpoints of the interval the function's limit must exist at that endpoint,for which it has to be defined in its neighborhood,but we don't know anything about whether the function is always defined in the neighborhood.
Please help...
Penny Nom lui répond.

Base 6 2014-09-10

Amanda pose la question :
using base 6, what is the next number after 25? 35? 55? and 455?

I need to be able to show the base 6 material.
Penny Nom lui répond.

35 base 6 2014-09-10

Amanda pose la question :
Sorry I am having trouble understanding base,

35 in base 6 means 3 10's and 5 ones, which is the same ____ in base 10?
Penny Nom lui répond.

211(base x)=152(base 8) 2014-09-09

Vaidehi pose la question :
Find the base value (i.e. x):
211(base x)=152(base 8)
Penny Nom lui répond.

A second grade word problem 2014-09-09

Beth pose la question :
How do I explain to my second grader how to find the answer to the problem:
My tens digit is 8 more than my ones digit. My ones digit can not be zero.
Penny Nom lui répond.

A secret number 2014-09-08

jai pose la question :
it is smaller than half of 100, it is more than 4 tens and less than 5 tens, the tens digit is two more than the ones digit , together the digits have a sum of 6..... What is my secret number?
Penny Nom lui répond.

Cutting a round cake so that it doesn't dry out 2014-08-26

James pose la question :
I'm wondering if there's a simple way to calculate the area between two parallel chords of a circle equidistant from its diameter, or if I have the area, to find the distance between the two chords.
Here's my "problem". You may have heard of the way of cutting a round cake so that it doesn't dry out - make two parallel cuts (chords) the length of the cake, take the middle piece, then push the two pieces together.
So I know the area of a 12" cake, and I want say, exactly an eighth of the cake. How wide do I cut the centre piece? Now to get even more difficult, the next day I want another eighth from the centre. How wide do I cut the next pieces, and so on...? Thanks, James
Harley Weston lui répond.

The inverse of f(x) = x^2 - x 2014-08-22

Tyler pose la question :
Find the Inverse function of:
f(x) = x^2 - x
Robert Dawson lui répond.

A price increase and a consumption decrease 2014-08-16

sujan pose la question :
If the price of petrol increases by 25% and Rajesh intends to spend only 15% more on petrol then by how much % should he reduce the quantity of petrol he buys?
Penny Nom lui répond.

Multiplication in base five 2014-08-07

Alise pose la question :
Hi Maths Central!

I was wondering if you could help me with multiplying in base 5. I have read a question previously answered by you in regards to this but got fairly confused by it and was hoping you could help me with my question.

My question is: Multiply 1422 base 5 by 21 base 5 keeping these numbers and answer in base 5.

Would you also be able to explain how to get to the answer?

Thanks!
Penny Nom lui répond.

The sum of the first 50 terms of an arithmetic progression 2014-07-26

Joshua pose la question :
Hello ...my is Joshua...I'm a grade 11 student...I got a question

Calculate the sum of the first 50 terms of an arithmetic progression: 112:98:84
Penny Nom lui répond.

60% as much as $30. 2014-07-18

Kenneth pose la question :
Question from Kenneth:

Hello:

Do you know why some "as...as" phrases indicate multiplication?

For example, ? is 60% as much as $30. This is equivalent to 60% X $30 = $18. How does this make sense?

I saw this example in an old textbook on business mathematics, but the author did not explain why it is equivalent to multiplication.

I thank you for your reply.
Robert Dawson lui répond.

Selecting a meal at a school cafeteria 2014-07-18

Gil pose la question :
A school cafeteria offers 2 main entrees, 3 fruits, 4 vegetables, and 3 drinks. If a plate consists of 1 entree, 2 vegetables, 1 fruit, and 1 drink, how many different plates can a cafeteria manager make? Please explain how you derived at answer. Thank you
Penny Nom lui répond.

How can eight eights be 1000? 2014-06-20

Aamir pose la question :
The digit 8 if we add it 8 time in it the answer should be equal to 1000.it may possible.i.e., 8+8+8+8+8+8+8+8=1000
Penny Nom lui répond.

A reversed curved on a railroad track 2014-06-19

cherrielyn pose la question :
Assuming that earth is a sphere of radius 6380 km, what is the difference in the latitudes of two cities 270 miles apart positioned on the same meridian?

Thank you in advanced po! :)
Penny Nom lui répond.

Forming a cylinder from a square 2014-06-08

kalyani pose la question :
the curved surface of a cylinder is a square of diagonal 2*square root of 2. What is the area of the base of the cylinder?
Penny Nom lui répond.

6 inches of dirt in a baseball field 2014-06-01

Mary pose la question :
The baseball field is 20,000 Square feet, 6 inched deep I need to know how many cubic yards of dirt this will generate.
Penny Nom lui répond.

Overlapping sets 2014-05-23

daniel pose la question :
motors inc manufactured 325 cars with automatic transmission,216 with power steering ,and 89 with both these options. How cars were manufactured if every car has at least one option?
Penny Nom lui répond.

A piecewise graph 2014-05-10

Zoe pose la question :
Lightning Energy charges residential users for each unit of electrical energy bought from them each quarter, according to the scale below:
0-500 units cost 17 cents per unit
500-1500 units cost $85 plus 10 cents for each unit in the excess of 500
1500 or more units cost $185 plus 9 cents for each unit in excess of 1500
Sketch a graph showing the charge C as a function of U for up to 2000 electricity units
Penny Nom lui répond.

Percentage change 2014-05-09

hi pose la question :
the hw club had 46 members in sept. in april, the club had 24 members. what was the percent of change in the hw club's membership from sept. to apan increase or decrease in membership? ril? what is
Penny Nom lui répond.

What was the selling price? 2014-04-25

Con pose la question :
Apple built 40 32GB wifi iPads, gave away two in a contest, and sold the rest at two times the manufacturing price. If the company's total profit was $10,782, what is the selling price of one of these iPads?
Penny Nom lui répond.

A circle is divided into three sectors 2014-04-17

atolagbe pose la question :
the area of a circle is 154cm square. it is divided into three sectors such that two of the sectors are equal in size and the third sector is three times the size of the other two put together. calculate the perimeter of the third sector. take pi=22/7?
Penny Nom lui répond.

Converting to base 5 2014-04-10

Usama pose la question :
Convert the numbers used in the following expressions into those of base-five and solve :
21+34-108+62
Convert the result so obtained into decimal system and thus check your answer?
Penny Nom lui répond.

The locus of a point 2014-04-04

srishti pose la question :
A point P moves such that the difference between its distance from the origin and from the axis of x is always a constant c . what is the locus of the point?
Penny Nom lui répond.

9,-4,6,-8,3,... 2014-03-31

Alynna pose la question :
You are given the following pattern: 9,-4,6,-8,3,...
Create a formula for the nth figure.

I have trouble finding the formula, I need help trying to find it.
Penny Nom lui répond.

Graphing piecewise functions 2014-03-29

Rayven pose la question :
Hi! I'm in eighth grade, taking ninth grade algebra 1. I'm confused as to how to graph piecewise functions. I know that you have already answered a question similar to this (I did my research first) but it didn't completely help me on my homework. I have to graph piecewise functions for the specified domains, and create a table for the absolute values. I know that two bars around a number means absolute value (two bars around -2 makes it +2) , but how do I graph and chart the absolute value for the following:

f(x)= |x+3 | for -5≤x≤3

And then graph and chart: (on a separate graph):

f(x)= {x if x≤0
{x+1 if x <0

thank you!
~Rayven
Penny Nom lui répond.

Percentage increase of the population of a town 2014-03-28

hunter pose la question :
The population of a certain town in 1984 was 2900 people. The percent increase was 2.5% each year. What is the town's population in 2002?
Penny Nom lui répond.

An arithmetic sequence 2014-03-20

Xabiso pose la question :
The 10th term of an arithmetic sequence is 28 and the 7th term is 19. Calculate the common difference and the first term of the sequence.
Penny Nom lui répond.

40 meters increased by 20% 2014-03-14

Kyle pose la question :
I need help finding out this question: 40 meters increased by 20% Is the answer 800 or is it 8?
Penny Nom lui répond.

Three consecutive whole numbers 2014-03-13

Abhishek pose la question :
Three consecutive whole numbers are such that if they be divided by 5,3 and 4 respectively, the sum of the quotient is 40. What are the numbers?
Chris Fisher lui répond.

Determine the selling price 2014-03-08

augustine pose la question :
knowing an auctioneer charges a 7% fee and I know I want $74,400 what is the formula to determine selling price.
Penny Nom lui répond.

What are the possible lengths of the hypotenuse? 2014-03-07

audrey pose la question :
The three sides of a right angles triangle measure x-2, x+5, and 2x-1 in length. What are the possible lengths of the hypotenuse?

... I'm doing the equation c2=a2+b2 and subbing in the numbers but nothing makes sense
Penny Nom lui répond.

The inverse of y = 5^x 2014-03-07

Melody pose la question :
how do you find the inverse of y = 5^x
Penny Nom lui répond.

The diameter of the base of a cone 2014-02-23

elwin pose la question :
i have a sector of a circle that has 120 degree and 6 cm length. What will be the diameter of the base of the cone.
and what is the diameter of the angle is changed to 180.
Harley Weston lui répond.

Selecting a card 2014-02-16

Akarsh pose la question :
Cards numbered 1 to 1000 were put in a box.Ali selects cards at random.What is the probability that Ali selects a card containing at least one'3'?
Penny Nom lui répond.

A sequence 2014-02-10

Joshua pose la question :
hello..the question I have today is... A sequence... 1,5,14,30,55,91 find the general terms.
Penny Nom lui répond.

Conics 2014-02-01

Kassidy pose la question :
Hey, I have searched through all the questions about conics and how people use them in the real world, but none of them were very specific on how they are applied and the process, why it's so important etc. I have a project due asking these questions and it's been very difficult finding the right answer, if you could name jobs, how they are use and specifically applied that would be greatly appreciated.
Penny Nom lui répond.

A sequence 2014-01-30

joshua pose la question :
hi...really struggle with one question that the teacher gave us...
The sequence is 1,2,1,5,8,1,11,___,___
Penny Nom lui répond.

Counting in base five using words not digits 2014-01-25

Randy pose la question :
We all know how to count (in the base 10/decimal system) using words not numbers. For example: one, two, three, four, five, six, seven, eight, etc. However, in base 5 (for example) how would you count (in words). For sure - in base 5 the number 1 could be "one", the number 2 could be "two". However there seems to be no words to describe base 5 numbers beyond 0,1,2,3 and 4 (and perhaps 10). In base 5 the number 10 is not ten. Rather it is "five". In base 5 what word(s) describe numbers larger than 10? What words are used for 11, 12, 13, 14, 20, 21, 22, 23, 24, 30, 44,...etc. Also, consider a man and woman were married in the Gregorian year 1964. If they had an anniversary tomorrow - how long would you say they've been married in base 5 speak? In numbers their Golden Anniversary would note 200 years of marriage in base 5. How would you articulate their years together in base 5? I don't recall seeing verbiage to represent numbers in any system other than the decimal/base 10 system. Do such things exist for other systems?
Harley Weston lui répond.

An arithmetic sequence 2014-01-06

paris pose la question :
find the twenty-fifth term of an arithmetic sequence whose first term is 12 and whose common difference is -6
Penny Nom lui répond.

An infinite geometric series 2013-12-24

Muhammad pose la question :
The sum of an infinite geometric series is 15 and the sum of their squares is 45. Find the series
Penny Nom lui répond.

Find the next 3 terms of the sequence 2013-12-19

Lanelyn pose la question :
Find the next 3 terms of the sequence 2,3,9,23,48,87,__,__,__
Robert Dawson lui répond.

Base 5 arithmetic 2013-11-27

samuel pose la question :
Good day sir, please i don't understand when you say 4x4=13 in base five? In fact, am always having difficulties in addition, subtraction, division and multiplication of number in the same base other than base ten. Please can you give me one example each with details explainations?
Penny Nom lui répond.

The popcorn box problem 2013-11-07

Dave pose la question :
We know that calculus can be used to maximise the volume of the tray created when cutting squares from 4-corners of a sheet of card and then folding up.

What I want is to find the sizes of card that lead to integer solutions for the size of the cut-out, the paper size must also be integer. EG 14,32 cutout 3 maximises volume as does 13,48 cutout 3.

I have done this in Excel but would like a general solution and one that does not involve multiples of the first occurence, as 16, 10 cutout 2 is a multiple of 8,5 cutout 1.
Walter Whiteley lui répond.

A union and interception problem 2013-10-19

Zakir pose la question :
Sir, I have some problem in union there is a Question in a book find B set if A={2,4,6,8} , AUB={2,4,5,6,7,8} and A intersection B={6,8} plz tell me how can I find the B set
Penny Nom lui répond.

Base 5 arithmetic 2013-10-12

Obassy pose la question :
(4 2 4 3)-(1 3 x 4)=( Y 3 4 4),find the value of x and y in the subtraction above carried in base five?
Penny Nom lui répond.

Base 5 2013-09-30

Zakir pose la question :
Sir I wanna know something about base 5 number system Why we use it and who use this ? and what is the purpose of it
Robert Dawson lui répond.

The markup on a country maple bedroom set 2013-09-26

steven pose la question :
Bargain Furniture sells a five-piece country maple bedroom set for $1299. The cost of this set is $700. What are the markup on the bedroom set?
Penny Nom lui répond.

Intersection points and diagonals 2013-09-11

Kenneth pose la question :
I was wondering, is there a relationship between the number of sides of a regular n-gon and the number of times its diagonals intersect?
Ie:
4 sides=1 intersect (center, diagonals form an 'X' )
5 sides=5 intersects (diagonals form a star)
6 sides=13 intersects
And so on.
Chris Fisher lui répond.

The sum of all whole numbers from 1 to X 2013-09-06

Tim pose la question :
How do I develop a rule for the sum of all whole numbers from 1 to X when I have no idea how to do this
Penny Nom lui répond.

A sequence or a series? 2013-09-05

Rahul pose la question :
Whether the following sequence is increasing or decreasing? I even do not kow whether to call it a sequence or not. an = (1/(1+n))+(1/(2+n))+....+(1/(n+n)). I am confused. It looks like a series to me. Please help.
Regards,
Rahul
Robert Dawson lui répond.

8 numbers from 80 2013-09-04

susan pose la question :
Out of 80 numbers how many combinations of 8 are there and what are they.
Penny Nom lui répond.

More than half of the people said... 2013-08-26

Lucy pose la question :
Hi,
The question is:
Samoa 23%
Brazil 41%
Sri Lanka 52%
Senegal 39%
Armenia 37%
Croatia 20%
Why is the following statement true for the data above: More than half of the people said they were interested in Sri Lanka. The reason I don't understand the problem is that because the percentages add up to be greater than 100%, that means that the 500 people(as stated in the question) who participated in the survey got to pick more than once. Therefore, it is not 52% out of 100% anymore. Thanks for taking the time to answer my question.
Robert Dawson lui répond.

Tesseract 2013-08-22

Dan pose la question :
I am not a mathematician. This seems to me an intuitively simple enough problem that I very much need an answer to from someone who's mathematics are better than mine. Please help.

The question is: for a tesseract of side length = 1 what is the distance of the center of each cube from the center of the tesseract ?

I think I have calculated the distance of each vertex from the center, and of the center of each edge from the center, but the question above baffles me.

(anyone not having a clue what I am talking about can brush up here http://en.wikipedia.org/wiki/Tesseract )

Thanks in advance - Dan V
Robert Dawson lui répond.

Consecutive Numbers Question 2013-08-11

Lucy pose la question :
Hello,
I have a question about consecutive numbers. So lets say a question tells you to find what three consecutive numbers are that add up to a certain number. To calculate this, would you use 2x+1, 2x+3, 2x+5 or just x, x+2, x+4.
Also, the same question for even numbers. Would you use:
2x, 2x+2, 2x+4 or just x, x+2, x+4.
My math book is confusing because it uses the first strategy(the 2x+…) in some situations and the second strategy(x+…) in other situations. Thus, can you provide me an explanation of why you would use the strategy that is correct?
Specifically, my book answered this question: If “n” is the first of five consecutive odd numbers, what is their average, using n,n+2….=5n+20 and average is n+4(this is the answer),.
For the question: the sum of 4 consecutive odd integers must be:
Divisible by 8 but not necessarily 16(this is the answer), it used the strategy 2k+1, 2k+3…=8k+16.

Thank you so much for taking the time to answer my question.
Harley Weston lui répond.

Practical uses of trigonometry 2013-08-06

tharindu pose la question :
use of trigonometry
Penny Nom lui répond.

Slicing through a cone to form an ellipse 2013-08-06

Pulkit pose la question :
we get an ellipse on slicing through a cone. Is there a relation between central axis of the cone and this ellipse?
Does it pass through the any of the foci of the ellipse?
Chris Fisher lui répond.

The area of a semicircle 2013-07-28

Lucy pose la question :
Find the area of the the figure described: a semicircle with arc length 3 pi.
Penny Nom lui répond.

A geometric sequence 2013-07-16

Relebohile pose la question :
Find the n^th term of 3,6,9,12,24,48...
Penny Nom lui répond.

Three consecutive odd integers 2013-07-08

sparsh pose la question :
Three times the first of three consecutive odd integers is 3 more than twice the third. The third integer is:
Robert Dawson lui répond.

Inverse trig functions 2013-05-19

ky pose la question :
hello, so iv'e been asked to draw a triangle with sides of 3, 4, and 5. And find the measure of all three angle using sin-1, cos-1, tan-1. I got really confuse, I'm taking the SAT pretty soon and it would be great to get this... THANX
Penny Nom lui répond.

Points of intersection 2013-05-02

Bianca pose la question :
Find the sets of values of k for which the line y=kx-4 intersects the curve y=x^2-2x at two distinct points.
Penny Nom lui répond.

How do i reverse this formula? 2013-04-20

MK pose la question :
I have 22,000,000 worth of gold and wants to want to resell the gold back with a profit. Each transaction of gold will have a transaction fee of 15%, so if i resell the gold back at 22,000,000, I will only get back 18,700,000 after 15% transaction cut. The current formula is X-15%X = Y where X = 22,000,000 and Y = 18,700,000 Will u be able to come up with a new formula if we don't know the value of X but we know the value of Y
Something like this X-15%X = 22,000,000. How do i reverse this formula to find the value of X
Thanks
Penny Nom lui répond.

How do i write log_8(P) =7 in exponential form? 2013-04-14

nancy pose la question :
How do i write this in exponential form log8P =7
Penny Nom lui répond.

If 4 cooks can bake 8 pies in 6 hours????? 2013-03-18

Kenneth pose la question :
Hello:

I want to determine which quantities are directly and inversely proportional in order to determine the answer for the following:.

If 4 cooks can bake 8 pies in 6 hours, 2 cooks can bake how many pies in 4 hours?

Answer: 2 2/3 pies

Can someone fully explain what I need to know in order to determine what is directly and inversely proportional in the example above?

I thank you for your reply.
Robert Dawson lui répond.

Increasing and decreasing sales 2013-03-06

Meghan pose la question :
Pace Design's sales increased by 30% in the first year, increased by 60% in the second year, decreased by 60% in the third year and increased by 90% in the fourth year. What was the cumulative change in sales over the 4 years?
Penny Nom lui répond.

Your profit should be 20% of your cost 2013-02-21

anis pose la question :
if the customer says your profit should be 20% of your cost..

1) my selling value should be cost +20% of cost = SP

or

2)cost / 0.80 = SP which is correct...if the second answer is right how should i justify my customer
Penny Nom lui répond.

Write a rule for the sequence 2013-02-20

Angelia pose la question :
Write a rule for the sequence. Then, find the unknown term. 1 3/8, 1 ¾, 2 1/8, _______, 2 7/8 Think: The pattern is increasing. Add 1/6 to find the next term. Rule: _______________
Penny Nom lui répond.

How can I teach how to change bases? 2013-02-20

Tammy pose la question :
How can I teach how to change bases? For example 80 base 10 changed to base 3. Thank you!
Harley Weston lui répond.

A curve in 3-space 2013-02-14

pardeep pose la question :
we have to show that the curve r(t)=(cos t)i+(sin t)j+(1-cos t)k ,0<=t<=2pie; is an ellipse by showing it to an intersection of a right circular cylinder and a plane. i got the eqn. of the cylinder but did not get the eqn of plane.
Harley Weston lui répond.

Is a line lying in a plane an open or a closed region? 2013-02-13

pardeep pose la question :
please help with this question on the open and closed intervals :: Is a line lying in a plane an open or a closed region? my teacher says it is a closed region reasoning out that it contains all it boundary points. please help how is it so?
Harley Weston lui répond.

Multiplication in base two 2013-02-01

Michael pose la question :
multiply in the indicated base

110two*11two
Penny Nom lui répond.

The multiplication table for the different bases 2013-02-01

sylvia pose la question :
I am having a difficult time trying to figure out how to fill in the multiplication table for the different bases. i don't know how to get the numbers.
Penny Nom lui répond.

A triangular island 2012-12-29

Udit pose la question :
A long time ago Mr Gibson found an island shaped as a triangle with three straight shores of length 3 km,4 km and 5 km. He declared an 'exclusion zone' around his island and forbade anyone to come within 1 km of his shore. What was the area of his exclusion zone?
Penny Nom lui répond.

A raised bed in the shape of an octagon 2012-11-22

pat pose la question :
I want to make raised-bed gardens - usually 4' square, but want to be more creative by creating octagonal boxes. The ideal size for square beds is 4'x4'. The boards are 8' long, so I want to get as much out of a board as I can. If I want an octagon with a diameter of 4', I think the sides would be (rounded off) about 1.5' each using 2 full boards with a little waste and the growing space would be less than a 4' square (16 square feet). If I want to increase the length of each side to 2' each (getting the max from a board), what will the diameter of this octagon be so I can determine the growing space of the box. (The reason a 4' square is important in gardening, besides maximizing the wood, is that a person can reach into the center to plant and pick veggies without stepping on the soil, so diameter is important). My math days are long over and I'm having trouble working with octagons! Thank you!
Harley Weston lui répond.

Difference of squares 2012-11-19

Qelibar pose la question :
Please factorise x^2y^2 - 4
Penny Nom lui répond.

Factor (6a^2-5a+1)(8a^2-6a+1)(12a^2-7a+1) 2012-11-16

bailey pose la question :
Factorise f(a)=(6a^2-5a+1)(8a^2-6a+1)(12a^2-7a+1) thus find [f(a)]^1/2
Penny Nom lui répond.

Stairs for the new community center, part 2 2012-11-13

Emily pose la question :
Plans for a set of stairs for the front of a new community center use the ratio of rise to run of 2 units to 5 units.

B. Sketch a set of stairs that meets the rise-to-run ratio of 2 units to 5 units.
Penny Nom lui répond.

A function with 3 asymptotes 2012-10-19

rimoshika pose la question :
find a function that have 3 Asymptotic : y=x/y=sinx/x=-1
Penny Nom lui répond.

The nth term of a sequence 2012-10-19

Emily pose la question :
I don't understand how to do this question:
Nth term for 9, 7, 5, 3, 1
Is there a fast way to do nth term for this question? Or in fact any question?
Penny Nom lui répond.

Revolutions per second 2012-10-18

Crystal pose la question :
Suppose a car wheel is 26 inches in diameter.
a) If the tire completes one rotation, how far would the car travel?
b) If the car is traveling at 60 miles per hour, how fast is the car wheel spinning in revolutions per second?
Penny Nom lui répond.

Functions 2012-09-18

nayeem pose la question :
I tried with many functions but I am not getting the exact values please help me
A give an example of a function whose domain equals the set of real numbers and whose range equals the set the set {-1,0,1}?
B Give an example of a function whose domain equals (0,1)and whose range equals [0,1] C.Give n example of a function whose is the set of positive integers and whose range is the set of positive even integers D. Give an example of a function whose domain is the set of positive even integers and whose range is the set of positive odd integers E give an example of function whose domain is the set of integers and whose range is the set of positive integers. F. Give an example of function whose domain is the set of positive integers and whose range is the set of integers.
please show me the work
Please give me the trick of finding such functions
Robert Dawson and Harley Weston lui répond.

Functions 2012-09-18

nayeem pose la question :
I tried with many functions but I am not getting the exact values please help me A give an example of a function whose domain equals the set of real numbers and whose range equals the set the set {-1,0,1}?
B Give an example of a function whose domain equals (0,1)and whose range equals [0,1] C.Give n example of a function whose is the set of positive integers and whose range is the set of positive even integers D. Give an example of a function whose domain is the set of positive even integers and whose range is the set of positive odd integers E give an example of function whose domain is the set of integers and whose range is the set of positive integers. F. Give an example of function whose domain is the set of positive integers and whose range is the set of integers.
please show me the work
Please give me the trick of finding such functions
Robert Dawson and Harley Weston lui répond.

Equivalent sets 2012-09-13

asif pose la question :
show that (-1,1)~(1,1) or give its counter example
Harley Weston lui répond.

The hypotenuse 2012-09-06

Jeevan pose la question :
how can i find the height and base of a right angle triangle if i have the hypotenuse only ?
Penny Nom lui répond.

A security code 2012-09-01

Breanna pose la question :
The code is made up of five two digit numbers from 01 to 20 entered in a certain order. How many different security codes are possible with this system
Penny Nom lui répond.

Minutes and seconds 2012-08-29

Casey pose la question :
I have to write a variable equation. The questions says there are 60 seconds. but we need to write and equation to solve for minutes. Is it 1/60 or 1/s
Robert Dawson lui répond.

An arithmetic progression 2012-08-22

A student pose la question :
the 3rd term of an A.PPP is 10 more than the first term while the 5th term is 15 more than the second.find the sum of the 8th and 15th terms if the 7th term is 7 times the first term.
Penny Nom lui répond.

John's electronic store 2012-07-25

Jora pose la question :
Electronic Store John opened an electronic store in December. During his first month, He sold 10 LCD TVs and 20 Plasma TVs. His income during that month was $12800. In January, he sold 25 LCD TVs and 40 Plasma TVs for an income of $27600. In February he projects to sell 30 LCD TVs and 50 Plasma TVs. If John expenses are $28900 in February, how much money will he have after paying the expenses?
Penny Nom lui répond.

A cylinder is to be filled with peas. 2012-06-12

Silje pose la question :
Hi! How can I solve the following question without the use of a calculator?

"A cylinder is to be filled with peas. It is done like this: At 12:00 o'clock you put 1 pea in, at 12:01 you put 2 peas in, at 12:02 you put 4 peas in, at 12:03 you put 8 peas in, and so on. This continues until 14:00 o'clock (two hours later), when the last peas are put in and the cylinder is full. At what time is the cylinder half full?"
Robert Dawson lui répond.

Expanded exponential form? 2012-06-12

Ramon pose la question :
express the numbers 990 614 000 005 in expanded exponential form.
Harley Weston lui répond.

A geometric sequence 2012-06-10

vicki pose la question :
The sum of the first three terms of a geometric sequence of positive integers is equal to seven times the first term, and the sum of the first four terms is forty-five. What is the first term of the sequence?
Penny Nom lui répond.

The area of a semicircle 2012-05-28

Rebecca pose la question :
how do you find the area of a semi circle and then how do you add the area of a semi circle and the area of a rectangle?
Penny Nom lui répond.

Division in base eleven 2012-05-27

Zoe pose la question :
How do you divide numbers that are in base 11?

For example;

9A7A6A divided by A
Penny Nom lui répond.

The nth term 2012-05-05

Justin pose la question :
Which expression can be used tofind the nth term in this sequence? 94,75,56,37,18,.....
My choices are
A. -19n=113      B. -21n+115
C. -19+75      D. 21n+73

Please explain how to get the correct answer. I think it is A. but I am not sure,
Penny Nom lui répond.

How to find the base length of a isosceles triangle if only the sides are given? 2012-04-25

aqilah pose la question :
how to find the base length of a isosceles triangle if only the sides are given?
Chris Fisher lui répond.

The inverse of y = x^2 - 2x 2012-04-20

Shona pose la question :
How do I Find the inverse of the function y= x^2 - 2x ?
Penny Nom lui répond.

A semi-circular roof gutter 2012-04-09

Kyle pose la question :
A semi-circular roof guttering contains some water.
The cross-section of the guttering has a diameter of 10 centimetres. The surface of the water collected in the guttering is 8cm. What is the depth of water in the gutter?
Penny Nom lui répond.

1+2+4+8....= -1 2012-04-02

Andy pose la question :
In this minutephysics video, it's claimed that 1+2+4+8....= -1 Is this true, and if so, how?
< href="http://www.youtube.com/watch?v=kIq5CZlg8Rg">http://www.youtube.com/watch?v=kIq5CZlg8Rg
Robert Dawson lui répond.

The power set of A 2012-03-24

rashdin pose la question :
Can you find a set A, |A|=4 and define a bijective function between A and P(A)?
Penny Nom lui répond.

The length is inversely proportional to the width 2012-03-18

David pose la question :
For a given set of rectangles, the length is inversely proportional to the width. In one of these rectangles, the length is12 and the width is 6. For this set of rectangles, calculate the width of a rectangle whose length is 9
Penny Nom lui répond.

Forming a triangle from 3 line segments 2012-03-15

rustom pose la question :
A point X is selected at random from a line segment AB with midpoint 0. Find the probability that the line segments AX, XB, and A0 can form a triangle.
Penny Nom lui répond.

An increase/decrease in profit 2012-03-13

Thanikasalam pose la question :
It is understood that increase/decrease in profit for current year compared to the previous year is done by the formula (x-y)/y, with x=profit on current year and y=profit on previous year. How do we derive this formula?

If we work on this formula of calculating increase/decrease in profit, we get x/y-1

* = (x-y)/y
= x/y - y/y
= x/y - 1

How do you justify the 1 in the equation above. How to derive the formula and how do i prove it?
Penny Nom lui répond.

Four digit combinations from 1,2, ..., 9 2012-02-26

Errol pose la question :
show me a list with all four digit combination numbers from 0 -9
Penny Nom lui répond.

A geometric sequence 2012-02-24

Camille pose la question :
Find x if the sequence 5,10,x+2 is geometric.
Penny Nom lui répond.

If x ix directly proportional to y then ... 2012-02-19

Crystal pose la question :
I understand that we say x and y are proportional, then y = kx.
Generally when we say x is proportional to y, we think that when x increases y increases.
Now I am questioning whether that is actually true.
If k is negative, then when x increases, y DECREASES.
My question is does this mean this statement is incorrect:
If x is proportional to y, when x increases, y increases proportionally.
Is it more correct to say:
If x is proportional to y, when x increases, y either increases proportionally or decreases proportionally.
Along the same line of reasoning, when x is inversely proportional to y, we think that when x increases y decreases, but that is true only if k is positive.
Is that correct?
Harley Weston lui répond.

Figures with dots 2012-02-15

A pose la question :
Okay so my daughter came home and had this question for homework from her teacher. I have no idea what it means HELP!!
The question shows a figure that is a square. It has 5 dots on the top, bottom and on the sides looks similar to this:
. . . . .
.       .
.       .
.       .
. . . . .
they want to know 3 more ways to show the number of dots in the figure. They have already shown one with just counting them and the other one that they showed was circling the four corner dots and then taking the dots in between with a number sentence set up like this: 4+4*(5-2) = 4+4*3= 16. They also besides giving 3 ways want us to write a number sentence and an algebraic sentence to show the number of dots in the figure with "n" sides. Please help! So confusing ! I don't know if my square turned out or not but it should be 5 across the top and bottom and on the sides and no dots in teh middle it is just the outside.
Penny Nom lui répond.

Can the result of the calculation be 2? 2012-02-09

Thomas pose la question :
You have the digits 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9 in a random order side by side and put randomly between two digits a colon, so that a division comes into existence. Can the result of the calculation be 2?
Robert Dawson and Chris Fisher lui répond.

A tree growth modelled by a geometric series 2012-02-08

Steph pose la question :
Hi I am really struggling with this question please help !!!!
a pohutukawa tree is 86 centimetres when it is planted. in the first year after it is planted , the tree grows 42 centimetres in height.Each year the tree grows in height by 95% of the growth of the previous year. assume that the growth in height of the pohutukawa tree can be modelled by a geometric sequence.
A)find the height of the tree 5 years after it is planted and figure out the maximum height the pohutukawa tree is expected to reach in centimetres
Penny Nom lui répond.

Notation for the second derivative 2012-02-06

Shafira pose la question :
In all math textbooks, it is written that d/dx ( d/dx) (y)= d2y/dx2. Why do they write it as d2y/dx2, not as d2y/d2x2?
Robert Dawson lui répond.

Two sectors of a circle 2012-02-03

Wayne pose la question :
I am not even sure what to ask. I have to two lengths of feet and an angle of degrees, and I have to find the area?
**Problem attached

Thanks,
Wayne
Penny Nom lui répond.

Properties of real numbers applied to subsets 2012-02-01

Mark pose la question :
Hello - The questions that I have for you is do the properties of real numbers (such as the associative, commutative, identity, inverse, and distributive law) apply to ALL the subsets of real numbers? In other words, do all those properties work for the Natural Numbers? The Whole Numbers? And so on and so forth. I understand that they are all real numbers, but for instance: the identity is whenever you add zero to a number, you get that number back. But does that work with, say, with only the odd numbers? Zero isn't odd so can that property actually apply to JUST the odd numbers? Any consideration would be greatly appreciated!
Robert Dawson lui répond.

1 + 3 + 3^2 ...+3^(n-1) = 3^n - 1/2 2012-01-27

Vicki pose la question :
I am trying to find out how to do show how this proof was worked.
Here is the end result 1 + 3 + 3^2 ...+3^(n-1) = 3^n - 1/2

This equation was used to find the number of white triangles in the Sierpinski Triangle
Walter Whiteley lui répond.

Two shapes 2012-01-06

muhammad pose la question :
Question from muhammad, a student:

a boy has two pieces of wire each 99cm long .he bends them into the shapes shown below.calculate the radius of each figure,giving each answer to two decimal places.figures are one is semicircle and other on is half of the semicircle.
Harley Weston lui répond.

A 46% increase 2012-01-03

kabilan pose la question :
increase a price of £8.24 by 46% and give the answer to the nearest penny
Robert Dawson lui répond.

The number of digits in a number base m 2011-12-22

Jash pose la question :
Assume there is a number system of base m.

The one property of this system is: If 2 numbers written in this system, which have 'a' and 'b' as the number of digits are multiplied, then the product of the 2 numbers will have a number of digits which is a function f(a,b).

In other words, as long as the number of digits of the 2 numbers are constant, the number of digits of their product is a constant.

Find m.
Robert Dawson lui répond.

Three consecutive numbers 2011-11-29

Michael pose la question :
Find three consecutive numbers such that the second number squared is equal to the first and third added together
Penny Nom lui répond.

Converting from base 4 to base 10 2011-11-29

anjg pose la question :
How to convert base 4 number 2^11 to base 10 number?
Penny Nom lui répond.

Four carpenters can build eight houses in 10 days. 2011-11-23

Kenneth pose la question :
Four carpenters can build eight houses in 10 days. Two carpenters can build how many houses in 15 days?
Penny Nom lui répond.

What was the cost price of the article? 2011-11-10

tashana pose la question :
By selling an article for $320,the profit was 20% of the cost price.what was the cost price of the article.
Penny Nom lui répond.

The sum of a series 2011-11-07

Rattanjeet pose la question :
Find the sum of 1(1/2) + 2(1/4) + 3(1/6) + 4(1/6)(3/4) + 5(1/6)(3/4)2 + 6(1/6)(3/4)3+ ... where 1/6 + (1/6)(3/4) + (1/6)(3/4)2 + ... constitutes a geometric series.
Penny Nom lui répond.

A scale drawing 2011-10-30

aretha pose la question :
i have a scale drawing of a house floor plan, don't understand how to find the answer. the drawing is 1in: 3ft. need to find the length / width/and the actual length/width of the living room,kitchen, 3bedrooms deck,sitting room, entry, and closet
Penny Nom lui répond.

Three consecutive terms of an arithmetic sequence 2011-10-30

Juliette pose la question :
Find X when x, 1/2x + 7, 3x -1 are consecutive terms of an arithmetic sequence.
Penny Nom lui répond.

Expanded form 2011-10-12

Chris pose la question :
Write this number in expanded form
4 326 180 501

Thanks!!!
Penny Nom lui répond.

Three consecutive odd integers 2011-10-07

Muneera pose la question :
Find 3 consecutive odd integers so that 3 times their sum is 5 more than 8 times the middle one?
Penny Nom lui répond.

A reservoir has the shape of an inverted cone 2011-10-03

Roger pose la question :
a reservoir has the shape of an inverted cone whose cross section is an equilateral triangle. if water is being pumped out of the reservoir at a rate of 2m^3/sec, at what rate is the depth of the water changing when the depth is 40 meters?
Penny Nom lui répond.

58 choose 4 2011-08-26

Jean pose la question :
Using only the numbers 1-59, how many times would the number 23 appear in combinations of 5 numbers?
... Can a list be provided as well?
Thank you very much,
Jean
Penny Nom lui répond.

Two line segments in the plane 2011-08-15

Tim pose la question :
For this problem I actually have tried to visualise the image in my head many times. This question makes my head spin.

Four points lie in a plane. They are partitioned into two pairs so that the sum of the lengths of the segments joining the points of each pair has the minimal possible value. Prove that these segments have no common points.
Chris Fisher lui répond.

A sequence 2011-08-14

intesar pose la question :
how do i figure this out 0,1/6,2/9,3/12
Penny Nom lui répond.

The third term of a sequence 2011-08-13

sammantha pose la question :
Find the 3rd term of the sequence, an=1.5(4)n - 1.
Penny Nom lui répond.

Infinite Logarithmic Series 2011-08-08

Sourik pose la question :
Dear Expert,

In my Amithabha Mitra and Shambhunath Ganguly's "A Text Book of Mathematics" I found the formula of log (1+x) where the base is e and x lies in between -1 and +1.As I want to learn Mathematics,I am not satisfied with the mere statement of the formula.Please help giving me the full proof.
Thanking you,
Sourik
Robert Dawson lui répond.

The nth term of a sequence 2011-07-01

Rachel pose la question :
I am trying to help my son get ready for our Aims test and I am not much help. The sequence is 2,5,10,17 The question is which equation represents the rule for finding the nth term for this sequence

a. an=n + 1
b. an=2n2
c. an=n2+1
d. an=2n+1
Penny Nom lui répond.

The nth term 2011-04-30

Samantha pose la question :
predict the general term, or the nth term, An for the sequence.
1/2,2/3,3/4,4/5,5/6
Penny Nom lui répond.

Find the rate at which the searchlight rotates 2011-04-17

Meredith pose la question :
A searchlight is position 10 meters from a sidewalk. A person is walking along the sidewalk at a constant speed of 2 meters per second. The searchlight rotates so that it shines on the person. Find the rate at which the searchlight rotates when the person is 25 meters from the searchlight.
Penny Nom lui répond.

sin x = -0.25 2011-03-29

Wayne pose la question :
How do you solve for x in the equation sin x = -0.25

the answer is 3.394 and 6.030 but I don't know the steps they used to calculate this
Penny Nom lui répond.

A true or false trig question 2011-03-24

Abeth pose la question :
True or False: Since cot (theta) = cos (theta)/sin (theta), if cot (theta) = 1/2, then cos (theta) =1 and sin (theta)=2. My answer before was true, but not my answer is false. Can you give me a solution on this matter. thanks.
Penny Nom lui répond.

A 15% increase 2011-03-22

Abeth pose la question :
Bobby dela Cruz is the purchasing agent for school supplies of a certain university. Because of new research projects, Bobby ordered an additional 32,500 worth of supplies this month. This is a 15% increase from last month. What was the value of the school supplies that Bobby ordered last month?
Robert Dawson lui répond.

Three consecutive odd numbers 2011-03-11

George pose la question :
Write an equation three consecutive odd numbers whose sum is 75
Penny Nom lui répond.

A family of circles 2011-03-01

steffi pose la question :
Find the equation of the family of the circle passing through the the point of intersection of x^2+ y^2 -4x-28=0 and x^2 +y^2 -4x-20+52=0; the member tangent to x=7.
Penny Nom lui répond.

Converting base 3 to 5 2011-02-28

Harry pose la question :
Hey Math Central, I came across your website and im in need of help on my maths c assignment. I have to convert base 3 to 5 without converting back to ten. I heard that you can use patterns in 3 and 5 to make an equation but im not sure how to and i also heard you can use logarithms but i dont know how to use those so im kinda stumped.
Robert Dawson lui répond.

An imaginary infinite geometric tree 2011-02-18

Elise pose la question :
An imaginary infinite geometric tree grows 1m the first day. 2nd day 2 branches and right angles to each other and each 0.5 m long. 3rd day two new branches at ends of each of previous days' 2 branches, again at right angles, and only .25m long each.
And so on, infinitely.
Q: Use relationships of right-angled triangles and high school level knowledge of geometric series to show the tree height is limited to (4 + sqrt2)/3 m and width to (2(sqrt2 + 1))/3 m.
Robert Dawson lui répond.

Reversing the digits 2011-02-08

rejie pose la question :
if the digits are reverse , the number is 9 less than the original number.what is the equation?
Penny Nom lui répond.

Three consecutive numbers 2011-01-31

parth pose la question :
name 3 consecutive numbers,each less then a 100,the smallest # is divisible by 6 the next is divisibel by 5 and the largest divisible by 4
Penny Nom lui répond.

A player runs from second base to third base 2011-01-30

Marie pose la question :
A baseball diamond is a square with side 90 feet in length. A player runs from second base to third base at a rate of 18 ft/sec. At what rate is the area of the trapezoidal region, formed by line segments A, B, C, and D changing when D is 22.5
Distance A is the players distance from first base when running from 2nd to third. Distance D is his distance from 3rd base. Distance C is the distance from 3rd to 3rd to Home. Distance B is the distance from Home to First. I have found dA/dt in a previous problem.
Penny Nom lui répond.

The perimeter of a semicircle 2011-01-29

Keith pose la question :
I have the perimeter of a semi circle of 37 but how do I calculate the diameter from this. This is all the information I have.
Penny Nom lui répond.

The sequence 2,3,5,5,8,7,11 2011-01-19

taylor pose la question :
number relationship in number sequence 2,3,5,5,8,7,11
Chris Fisher and Penny Nom lui répond.

tanθ=1.192 2011-01-15

Adori pose la question :
Use a calculator to approximate two values of the θ (0 ≤θ≤2π) that satisfy the equation. a) tanθ=1.192

I do not understand how to find the second value of θ.
Harley Weston lui répond.

What is next in the sequence? 2011-01-13

jodi pose la question :
what is next in the sequence 1, 1/4, 1/9, 1/16, 1/25
Penny Nom lui répond.

Set notation 2011-01-10

Ron pose la question :
The question asked in a handout:

8k - 5 < 35, keI

I believe the answer to k is 5. But what does the k e(E) I mean in this?
Harley Weston lui répond.

Semicircles and the Pythagorean Theorem 2011-01-09

Jas pose la question :
Okay well, in math we are learning about the pythagorean theorem and we have to do a math journal on the question:

****Can you replace the squares (that are put on the sides of a right triangle) with semicircles and still get the same answer??

I do not understand because i tried doing an example and comparing it with a normal way of doing it and I didnt get the same answer!
Penny Nom lui répond.

A sector of a circle 2011-01-07

Alice pose la question :
the radius of a circle is 7cm the angle of the sector is 68 how do you find the
Penny Nom lui répond.

Line segments 2011-01-04

Izsak pose la question :
What is the formula to find the number of segments that can be named by a given number of points on a line?
Penny Nom lui répond.

[sec^2x]*[sec^2x] 2010-12-16

Hari pose la question :
[sec^2x]*[sec^2x]=...?
Penny Nom lui répond.

A geometric progression 2010-12-15

Abeth pose la question :
find the value of x so that 2(x-1), x+3, x will be a geometric progression.
Penny Nom lui répond.

A sector of a circle 2010-11-29

Mel pose la question :
Find the area of a sector of a circle that has a central angle of 13pi/18 and a radius of 12cm. Round answer to nearest 10th degree
Penny Nom lui répond.

Hours minutes and seconds 2010-11-26

beket pose la question :
I need to turn 1.486588292 into real time hours minutes and seconds. I keep getting multiple answers. Online conversions give me 1 hour 29 minutes and either 11 or 12 seconds. On the calculator I get 1 hour 29 minutes and 20 seconds. Can you explain how to turn this decimal into time?
Robert Dawson and Penny Nom lui répond.

Intersecting polygons 2010-11-17

Laura pose la question :
How can I estimate the amount of intersection (area or better a normalized number) between two polygons if I have the cartesian coordinates of their vertices?

Thank you in advance,
regards,
Laura
Robert Dawson lui répond.

The perimeter of a semicircle 2010-11-11

gayathri pose la question :
the area of semicircle is 1925sq.cm find perimeter
Stephen La Rocque lui répond.

Three consecutive odd integers 2010-11-07

karen pose la question :
find three consecutive odd integers such that twice the sum of the second and the third is 43 more that three times the first
Penny Nom lui répond.

How far must the pitcher travel to get to the ball? 2010-11-04

ken pose la question :
A baseball player bunts a ball down the first base line. It rolls 35ft at an angle of 26 degrees with the first base path. The pitchers mound is 60.5 ft from the plate. How far must he travel to get to the ball.
Penny Nom lui répond.

The base of an isosceles triangle 2010-10-24

Brian pose la question :
how can I find the base of an isosceles triangle from the height and the perimeter?
Penny Nom lui répond.

Four consecutive integers 2010-10-21

Mickey pose la question :
Find four consecutive integers such that the sum of the first three integers is 20 more then the fourth integer. I know that for consecutive integers the algebraic expression is x+x+1+x+2+x+3
Penny Nom lui répond.

A division sentence for an array 2010-10-05

Laura pose la question :
On a math test Grace needs to look at an array and write a division sentence for the array. Grace writes 18/3=6 on her answer sheet. Describe what the array on Graces test looks like.
Penny Nom lui répond.

A Taylor polynomial for (lnx)/x 2010-09-29

Dave pose la question :
I have a series problem that I cannot solve. The problem asks for you to compute a Taylor polynomial Tn(x) for f(x) = (lnx)/x. I calculated this poly out to T5(x) and attempted to use this to identify a pattern and create a series in order to calculate Tn(x). However, the coefficients on the numerator out to F5prime(x) are as follows: 1, -3, 11, -50, 274... Ok, so the negative is an easy fix -> (-1)^n-1. But the other coefficients are stumping me. I can't see any sort of pattern there and I've tried every trick I know. Is there another way to go about this? Thanks!
Chris Fisher lui répond.

rat sequence 2010-09-24

Vishal pose la question :
this is known as rat sequence. I want to know the logic pf this :-

1,2,4,8,16,77,145
Chris Fisher lui répond.

A reverse PST calculation 2010-09-23

Manning pose la question :
Hi, I'm a manufacturing contractor in Saskatoon. The way to calculate PST for us is using total contract amount x 70% then 5%. For example, contract amount of $100 x 70% x 5% = $3.5 (PST). The subtotal is using contract amount + PST. $100 + $3.50 = $103.50.

If you only know the subtotal is $103.50 including PST, how do you reverse calculation to get the contract amount?

Thank you very much for your help.
Harley Weston lui répond.

A taxi ride 2010-09-22

Jack pose la question :
A taxi ride costs you $2 for the first km and 10 cents for each tenth of a km thereafter. Sketch a graph of the total cost $C(x) for a ride of xkm, for 0 < x < 2. Hint: The graph is not smooth.

How will I start this question off? I tried the table of values method, and then graphed it, but it comes out as smooth,
Stephen La Rocque lui répond.

Find the point of contact of the circles 2010-09-20

Sandra pose la question :
If the center of circle A = (-1,-3) and the radius of it is √20, the center of circle B = (5,9) and the radius of it is √80. Find the point of contact of the circles A and B.
Janice Cotcher lui répond.

The nth term 2010-09-14

Anna pose la question :
The problem is 2n-2. find the nth term. I'm lost as how to even begin
Penny Nom lui répond.

Differentiable on an interval 2010-08-12

Dave pose la question :
Hi I was wondering if a function can be differentiable at its endpoint. For example if I have Y = X^2 and it is bounded on closed interval [1,4], then is the derivative of the function differentiable on the closed interval [1,4] or open interval (1,4). They always say in many theorems that function is continuous on closed interval [a,b] and differentiable on open interval (a,b) and an example of this is Rolle's theorem. Thank you for your help.
Robert Dawson lui répond.

An 18ft round pool 2010-07-19

christine pose la question :
will an 18ft round pool fit on a 12x16 ft rectangular cement slab?
Tyler Wood lui répond.

Remainders 2010-07-17

GARY pose la question :
WHAT NUMBER DIVIDED BY 11 LEAVES 1, DIVIDED BY 13 LEAVES 8, AND DIVIDED BY 17 LEAVES 3.
Chris Fisher lui répond.

A pattern in a puzzling sequence 2010-07-09

Martha pose la question :
A1 2 3 B 5 6 7 C 9 10 11 D 13 14 15

USE THIS PATTERN SUGGESTED TO HELP YOU FIND
THE MISSING TERMS IN THE PROBLEM BELOW:
a) H _ _ _ b) R _ _ _
c) _ _ 50 _ d) _ _ _ 63
e) _ @#$ where @ + # + $ = 258
Tyler Wood lui répond.

The product of 2 consecutive integers 2010-06-28

Sharon pose la question :
the product of 2 consecutive integers is -6 less than the square of the larger number. find the smaller number
Penny Nom lui répond.

The intersection of two graphs 2010-06-27

Austin pose la question :
In depth explanation of how to find the intersection points of functions y=-4t+300 and y=-4.9(t-5)^2+300
Stephen La Rocque lui répond.

Selling price, cost and profit 2010-06-22

Alex pose la question :
The profit on a certain television set is 16.5% of the cost price. If the profit is $330, Find:
a) the cost price
b)the selling price of the television
Penny Nom lui répond.

The area of a circle 2010-06-12

grier pose la question :
please,
what is the area of a semicircle with arc length 3pi?
Penny Nom lui répond.

A cylindrical vessel with belled ends 2010-06-01

George pose la question :
surface area of a vessel with a cylindrical length of 60 feet, a diameter of 10 feet, and with belled ends of 5-foot radius
Penny Nom lui répond.

Math in the workplace: nursing 2010-05-24

Taylor pose la question :
How is math used in the workplace - Nurse Anesthetist?
Penny Nom lui répond.

The number of gallons of water in a basement 2010-05-23

George pose la question :
A basement with dimensions 68 ft long by 42 ft wide by 10 ft deep is flooded to the ceiling calculate the number of gallons of water in the basement. 70
Penny Nom lui répond.

Divisibility by 3 2010-05-23

Cathleen pose la question :
To math central. I have to do a maths extension question that I don't understand. At first I thought I did. It is about the dividing by three. In one part of the question, it asks me to show that the rule of division by three does not work for 23142 with a little 5 down the bottom. What doe base 5 mean? We first thought that the little 5 down the bottom meant multiplying y the power of five. Can you please tell me what it means so I can finish this question?
Penny Nom lui répond.

The hypotenuse of a triangle 2010-05-22

linda pose la question :
find the length of the hypotenuse of a triangle with legs of 12in. and 17in. round to the nearest hundredth
Tyler Wood lui répond.

Percentage increase 2010-05-20

Rebecca pose la question :
Question from Rebecca:

In 2008 my land was valued at $84,000. In 2009 my land was re-valued at $235,000.00. What is the percent increase between the two values? I want to be able to express "the value was increased by x%."
Harley Weston lui répond.

The product of two consecutive even integers 2010-05-11

Terry pose la question :
The product of two consecutive even integers is 14 more than their sum. Find the integers.
Penny Nom lui répond.

The nth term 2010-05-09

Jessica pose la question :
what is the nth term of 3, 9, 19, 33, 51
please help
Walter Whiteley lui répond.

A geometric progression 2010-04-30

Kalyani pose la question :
sum of infinite geometric progression is 9 and common ratio is 1/10 then sum up to 8 terms is?
Chris Fisher lui répond.

Sales taxes in Quebec 2010-04-28

carole pose la question :
I work at a company where we use transport companies and we often get credits on their invoices. I need to know how to subtract the sales taxes from these credit amounts. (5% TPS and 7.5% TVQ). Is the equation: Amount / 1.05 = then this amount / by 1.075=?
Penny Nom lui répond.

4 + 10 + · · · + (6n − 2) 2010-04-21

Lan pose la question :
Find the sum 4 + 10 + · · · + (6n − 2). The answer is 3(n^2) + n. How?
Penny Nom lui répond.

The area of semi circle 2010-04-16

sagir pose la question :
how to find the area of semi circle?
Penny Nom lui répond.

A sequence 2010-04-13

Essence pose la question :
hello, I am having trouble doing my math homework. It asks me to write the first five terms of each sequence .I can not figure it out because it is a fraction.

The Problem Is:

{2n+1/2n}
Penny Nom lui répond.

A geometric sequence 2010-04-13

glen pose la question :
A geometric sequence has a first term of 0.1024, a second term of 0.256, and a middle term of 156.25. how many terms are there in the whole sequence? i know that r=2.5 but i dont know how to find how many terms there are.
Penny Nom lui répond.

Counting by sevens 2010-04-13

Larry pose la question :
Lee counted by 7's beginning with one of the whole numbers from 1 through 7, until Lee passed 1000. If Lee counted three of the following numbers, which number did Lee NOT count?

a. 107
b. 184
c. 534
d. 641

Robert Dawson and Penny Nom lui répond.

The area of a field of view 2010-04-07

Frank pose la question :
I know we have a field of view of 90 degrees and the distance we can cover is 6 miles. What is the area we can cover/view?
A formula would be nice to have since the diameter or distance of the wedge area can change and the degree of the field of view can also change.
Thank you and I look forward to hearing from you.
Frank
Penny Nom lui répond.

Body measurements 2010-04-06

Amirul pose la question :
Recently I'm proposing my research question to my teacher for my extended essay. I'm an IB student. My research question is regarding the estimation of human in buying trousers through reference of neck. What does the relation between the diameter of the neck and the diameter of the waist? I want to see how far does the estimation theory is true for different type of people with different BMI(body mass index)..

But teacher said that it is golden ratio...so nothing interesting... =( really??? But i search on net.... state that my idea seems do not have any relation with the golden ratio so far..... i just want ask you... am I able to perform in my extended essay if i continue with this research question??
Robert Dawson lui répond.

1/1+1/2+1/3... 2010-03-31

Mohd pose la question :
you explained the way of getting the summation of 100 series numbers but what is the summation of the numbers 1/1+1/2+1/3+1/4+1/5.............................+1/100
Robert Dawson lui répond.

The angle of intersection between two lines 2010-03-25

Madhumitha pose la question :
How to find the angle of intersection between a line x=249 and another line which is of the form y=m*x+c; Line1 has a slope of infinity so what does the angle of intersection turn out to be? Or how can i find it?
Chris Fisher lui répond.

Water in a culvert 2010-03-18

Chip pose la question :
Hello, I have a problem to which I know there must be an analytical solution - but as it has been 50 years since I studied math I can't remember quite how to do it!! I have a 12" round culvert in my yard that runs water all year. I would like to be able to calculate the flow through the culvert by measuring the depth of water flowing through and measuring the speed of the current. I can measure the depth and the speed, but I forget how to calculate the cross section of the flow. If you could help I would greatly appreciate it. Thank you
Penny Nom lui répond.

Angular velocity 2010-03-17

Lindsay pose la question :
Determine the angular velocity, in radians per second, of a 14-inch car wheel, if the car is traveling at 60 miles per hour
Harley Weston lui répond.

A 14 side well house cover 2010-03-12

Kenneth pose la question :
I am 35 yr I am wanting to build a well house cover. I'm trying to figure out how long the pieces need to be and what angle they need to be for a 4 ft dia with 14 side well house. I would love an answer but would also like to know how to figure it in the future. Thanks Kd
Harley Weston lui répond.

Prove A intersect B =X iff A = X and B = X 2010-03-06

Gloria pose la question :
how would you prove A intersect B =X iff A = X and B = X
Tyler Wood lui répond.

The base area of rectangular prism 2010-03-05

Desiree pose la question :
How do you find the base area of rectangular prism that has 4 cm by 4cm by 6cm ?
Penny Nom lui répond.

2+3 =10 and 7+2=63 and ... 2010-03-01

brenda pose la question :
if 2+3 =10 and 7+2=63 and 6+5 =66 and 8 +4 = 96 then 9+7+ ??????
its driving me crazy !!
Penny Nom, Claude tardif and Melanie Tyrer lui répond.

The hypotenuse 2010-02-27

Dannielle pose la question :
how do you find the hypotenuse if a=8 and b=6?
Penny Nom lui répond.

The test for some disease is 99% accurate 2010-02-24

baaba pose la question :
Assume that the test for some disease is 99% accurate. If somebody tests positive for that disease, is there a 99% chance that they have the disease?
Chris Fisher lui répond.

A geometric sequence 2010-02-22

Kelsey pose la question :
_, 2, _, _, 250, _

i don't know how to fill in the missing terms
Penny Nom lui répond.

The first five terms of a sequence 2010-02-14

Joanne pose la question :
Find the first five terms of the sequences with the nth term given as follows. n^2+3n
Penny Nom lui répond.

Can a line segment curve over two planes? 2010-02-14

Graham pose la question :
I am working on a math fair project. Can a line segment curve over two planes? Such as, if I had a three dimensional L bracket and I drew a line segment on it with a marker starting on the bottom of the L and had it curve around the corner and up the top, would it still be considered one line segment? Or is that two line segments? Is there a rule that a line segment can only occupy one plane? Thank you. Graham
Chris Fisher lui répond.

A square corner 2010-02-11

Trevor pose la question :
I am building a new house and wish to set it out on site with the use of profile boards and string. I want to be certain it is correct in terms of squareness. I have a vague idea that the square on the hypotenuse should be equal to the sum of the squares of the other two sides.

I get a little lost here and need some help. The building is a rectangle measuring 40x30 feet to exterior brickwork. I guess that the length of the hypotenuse should be exactly the square root of the combined squares of the two sides.

Using the above measurements could you give me calculations from nuts to soup as to the correct length of the diagonal. And what adjustments are needed if everthing is not in accord.

Trevor.
Robert Dawson lui répond.

A sequence 2010-02-07

Shalev pose la question :
hi,

i had a job interview yesterday. it had mathematical questions. couldn't solve 1. i m obsessed with it. please find out what the answer is..

it goes like this: 2,4,5,5,8,6,_,_,14,8

thank u very much
Claude Tardif lui répond.

The perimeter of a semicircle 2010-02-04

Sarah pose la question :
The perimeter of a semicircle is doubled when the radius is increased by 7. Find the radius of the semicircle.
Tyler Wood lui répond.

A sector of a circle 2010-02-04

trisha pose la question :
Given a circle with a radius of 6 inches. Find the area of the sector that is formed by an arc of 36 degrees. Round your answer to the nearest tenth of an inch.
Penny Nom lui répond.

Consecutive even integers 2010-02-03

cassandra pose la question :
find 2 consecutive even integers whose sum is 34

find 3 consecutive even integers such that 3 time the middle interger is 10 more than the greatest.
Tyler Wood lui répond.

A sequence 2010-01-27

Haku pose la question :
if there are 8 dots in the first shape, 13 in the second, 19 in the third, and 26 in the fourth, then what is the formula?
Penny Nom lui répond.

A sequence 2010-01-22

brahmaji pose la question :
0 7 26 63 _ 215 342 fill the blank? find the missing number
Robert Dawson lui répond.

Angle of incline 2010-01-20

Alan pose la question :
how do I fnd the angle of an incline with a measurement of 0.042 with an adjacent of 1.2mtrs?. Thank You
Penny Nom lui répond.

Percentage increase from a negative to a positive 2010-01-12

Greg pose la question :
If a company had a net lost in 2005 of $11,234 and net income of $3231 in 2006, what is the percentage annual growth in income between the two years?
Robert Dawson lui répond.

Improper fractions 2010-01-12

Blanca pose la question :
Between which two consecutive natural numbers does the improper fraction 57/56 lie?
Robert Dawson lui répond.

The domain, range and inverse of a relation 2010-01-08

Nazrul pose la question :
Given that A={-2,-1,0,1,2}, S={(x,y): x belongs to A, y belongs to A and y^2=x}. How can I find the domain and range of the relation S. What is the inverse relation of S. Please show me the process in details. Thank you.
Penny Nom lui répond.

The area of a sector 2010-01-07

angelkem pose la question :
how do you get the area of the circle, the sector, the shaded sector, non shaded sector and its total area if the diameter is 20 cm and each area of the circle is 45 degrees?
Penny Nom lui répond.

Consecutive odd intergers 2010-01-06

keyanna pose la question :
list five consecutive odd integers, starting with -3
Robert Dawson lui répond.

Holiday for 7 golfers 2010-01-05

Andy pose la question :
I am having difficulty scheduling pairings for a forthcoming Golf holiday. There are 7 players and we will be playing 7 rounds - each round will be a 3 ball and a 4 ball. I am trying to work out a schedule that means everyone plays with each other roughly the same number of times (with a minimum of, say, 3 times if possible). Also, we are looking to ensure everyone plays in roughly the same number of 3 and 4 balls. Any suggestions would be much appreciated (we leave in 10 days time). Thank you.
Victoria West lui répond.

Profit increase from 10% to 15% 2010-01-03

taha pose la question :
A shopkeeper sold a pen for $13.20 to a make a profit 10 percent.In order to earn a profit of 15 percent,he should have sold it for?
Penny Nom lui répond.

Triangles on a base of 2.4 meters 2009-12-26

Allan pose la question :
Please,How do I calculate the height of a triangle when I only know the width of the base line,It is 2.4 mtrs.
Thankyou very much.
Penny Nom lui répond.

The acute angle formed by intersecting lines 2009-12-17

Katie pose la question :
To the nearest tenth of a degree, find the size of the acute angle formed by the intersecting lines 3x + 2y = 12 and x - 2y = -2. Was is necessary to find the intersection point?
Robert Dawson lui répond.

The second derivative of y = x³ (x² + 5) 2009-12-14

Kyrie pose la question :
Find d²y/dx² for this function:

y = x³ (x² + 5)
Penny Nom lui répond.

A circle problem 2009-12-14

Fawad pose la question :
AP is a tangent at P to a circle centre O, where AP=6cm. The straight line AQC is such that QC= 9cm. Find the length, in cm of AQ.
Chris Fisher lui répond.

Bases larger than ten 2009-12-14

Nick pose la question :
For numbers in bases larger than ten, what are the digits by mathematicians' conventions?

I assume the first 10 are always 0-9. I know two computer science conventions (for hexadecimal (A-F case-insensitively) and for base 85 (case-sensitivity plus 23 other characters)) and as a school student I learned that base 12 uses either T and E (which confused me when I thought they stood for Eleven and Twelve) or A and B, the latter as capitals only. Clearly, these conventions are in conflict.

I saw your reply in http://mathcentral.uregina.ca/QQ/database/QQ.09.99/magin1.html as accessed a few minutes ago but hope that in the 10 years since then mathematicians have arrived at a convention. Have they?
Thank you.

--
Nick
Claude Tardif lui répond.

A number base that's not a positive integer 2009-12-11

Nick pose la question :
Is it possible for a number to have a base that's not a positive integer? Base 1 gives a result that's meaningless but possible. I have no concept of a base 0, a negative base, or a fractional base, never mind any other base. I think there isn't any base that's not a positive integer, but, knowing that math keeps jumping ahead and sometimes has inventions before anyone knows how to exploit them, I think I'd better ask.

Thank you.

Nick
Robert Dawson and Claude Tardif lui répond.

7 36 14 18 28 9 56 x y 2009-12-06

lisa pose la question :
what is the sequence of x and y
7 36 14 18 28 9 56 x y
Penny Nom lui répond.

What number comes next? 2009-11-25

Mark pose la question :
Can someone help and give me the break down of how to solve. 5,3,1,-1
Penny Nom lui répond.

The point of intersection of the pair of straight lines 2009-11-19

Stephanie pose la question :
Find the point of intersection of the pair of straight lines:
y=-3x-9
-y=4x+2
x = _______ and y = ________

I am totally confused. Please help
Robert Dawson lui répond.

A baseball diamond 2009-11-18

maelee pose la question :
the official distance between home plate and second base in baseball diamond is 120ft. Find the area of the official ball diamond & the distance between the bases.
Robert Dawson, Chris Fisher and Penny Nom lui répond.

6 numbers from 53 numbers 2009-11-17

MIGUEL pose la question :
IM A STUDENT IN HIGH SCHOOL AND IM HELPING THE SOCCER COACH WITH PLAYS SO I NEED ALL THE POSSIBLE NUMBER COMBINATIONS OF NUMBERS 1- 53 IN SETS OF SIX THE NUMBER CAN ONLY BE USED ONCE IN EACH SET.
Penny Nom lui répond.

A sequence of letters and numbers 2009-11-10

Maria pose la question :
What is the last ten letters and numbers in the following series and how do I work it out so I can explain it to an eleven year old. J1F8M1A0M1J0J1
Robert Dawson, Claude Tardif and Harley Weston lui répond.

A drawing of a baseball diamond 2009-11-09

Beth pose la question :
My husband has a drawn diagram on a piece of paper of a baseball diamond. He knows that on the paper 1 1/16" (1.6875") = 90 actual feet. How do we calculate how many feet 5 7/8" on the paper would be?
Penny Nom lui répond.

Consecutive odd integers 2009-11-09

Erin pose la question :
I'm having trouble with consecutive integers. i know it goes n + n + 1 + n + 2 and so on, but if its odd then do the numbers change to odd ones? i don't know the question is: the sum of four consecutive odd integers is -72. write an equation to model this situation and find the values of the four integers
Robert Dawson and Penny Nom lui répond.

What's the next term? 2009-11-03

bharat pose la question :
if
1=5
2=25
3=325
4=4325
5=?
Robert Dawson and Penny Nom lui répond.

The extended real numbers 2009-11-02

Justin pose la question :
Hello there, I was wondering is the set of extended real numbers a closed set or an open set?

Justin
Robert Dawson lui répond.

Consecutive positive integers 2009-11-01

Madi pose la question :
I'm doing my homework, and there are questions on Consecutive Positive Integers. I was just wondering, what is a consecutive integer? Or to be more specific, what is a consecutive POSITIVE integer?
Penny Nom lui répond.

The intersection of two graphs 2009-10-30

asma pose la question :
by using the suitable scales,draw both the graph of x/2 + y/4 =3 and y=2 on the same graph paper.Find the points of intersection of the two graph.
Penny Nom lui répond.

Graphing y=(4-x^2)^5 2009-10-25

natalie pose la question :
I want to graph the curve of y=(4-x^2)^5 without using a graphing calculator. To do this, I'm suppose to find: domain, y and x intercepts, asymptotes, intervals of increase/decrease, local max/min, concavity and points of inflection. I got all the way to the step where I'm solving the concavity and I'm stuck. I found the f"(x) and it came out to be really large polynomial. I want to know how I can solve for the x of f"(x) without the use of a graphing calculator, when the polynomial has x^6 and x^8. Thank you so much, natalie
Harley Weston lui répond.

Four consecutive odd integers 2009-10-24

Tonya pose la question :
the sum of four consecutive odd intergers 2008 what are the intergers
Penny Nom lui répond.

What jobs use conics? 2009-10-22

denise pose la question :
i have to type a paper on what jobs use conics and i can not find anything can you help

thanks
Denise
Penny Nom lui répond.

The inverse of f(x)=-1/x^2 2009-10-22

Jasmine pose la question :
how to solve f(x)=-1/x^2 --> find f-1[x], than state if its a function
Harley Weston lui répond.

A sequence 2009-10-20

Alyce pose la question :
The rule of this sequence is k=1/8n. Find the 8th term of the sequence.

1/8, 1/4, 3/8, 1/2, ...
Thanks!
Penny Nom lui répond.

The hypotenuse of a right triangle 2009-10-18

steven pose la question :
the perimeter of a right triangle is 20 cm. its area is 15 sq cm. find its hypotenuse.
Penny Nom lui répond.

The next three terms 2009-10-16

Shawn pose la question :
I'm a parent and don't know how to help my 6th grader solve for this problem.

Name the next tree terms in this sequence and tell the rule used to find each:

-1,0,1,0,1,2,3,8,25,.....
Chris Fisher lui répond.

What is the next term? 2009-10-04

julia pose la question :
patterns 18 46 94 63 52 61 what is the next one?
Penny Nom lui répond.

How many terms are there in this sequence? 2009-09-28

tabby pose la question :
How many terms are there in this sequence?
5,1,-3,...,-111
Penny Nom lui répond.

Seven circles 2009-09-20

Bobbi pose la question :
try to put number 1 to 7 in seven circles (one in the middle, 3 on top, 3 below) so the numbers in each row of three circles--vertical, horizontal, and diagonal -- add up to 12. Each number can be used only once.
Stephen La Rocque lui répond.

Segments of a ring gasket 2009-09-20

Robert pose la question :
I am in the process of making an Excel spreadsheet in which our sales team just needs to enter the outside diameter, inside diameter, and number of segments to price ring gaskets that are too big to fit on a sheet of material and need to be cut into segments. With your help I was able to create a spread sheet that can calculate the Chord lengths, and Segment height on a single gasket segment. I am now stuck trying to come up with a formula to figure out the height of the second segment when it is stacked on the first segment, then use it to add more depending on the quantity of segments needed. I have an illustration below showing 2 segments (of a gasket that was segmented into 4 pieces) stacked together. I need to find a formula to get the dimension from "A" to "B".
Harley Weston lui répond.

A sequence 2009-09-19

Oliver pose la question :
I am struggling to work out the missing terms in the following sequence:

1, 3, _, 7, 11, 18, _
Chris Fisher lui répond.

Cubes and squares 2009-09-16

Stanley pose la question :
What is a three consecutive digit number like 5,6,7 , which is two less than a cube and two more than a square?
Robert Dawson lui répond.

A sequence 2009-09-15

Derek pose la question :
what are the next four numbers in this sequence 1/8, 1/4, 3/8, 1/2...
Penny Nom lui répond.

The nth term of a sequence 2009-09-11

Michael pose la question :
My son has this question as part of his key stage 3 maths homework-

The nth term of a different sequence is n - 2/n^2.

We've got to find the first three terms of the sequence.
Claude Tardif lui répond.

Bisecting rays 2009-09-09

frank pose la question :
Ray OC bisects angle AOB, ray OD bisects angle AOC, ray OE bisects angle AOD, ray OF bisects angel AOE, and ray OG bisects angle FOC: if angle BOF=120 degrees, then find angle DOE? Confused!
Penny Nom lui répond.

The intersection of two graphs 2009-09-02

Jaqueline pose la question :
Find the points of intersection of the graphs of the equations

x^(2 )+ y^2=25 and 2x + y = 10
Penny Nom lui répond.

Price increases and decreases 2009-09-02

craig pose la question :
I work for an industry that bases it price increases and decreases on commodity pricing - Customer get confused on how/why we calculated new prices due to movement in the market - Price go up x% for every $10 of movement in the market -

For this example-
Movement went down by $30 and it is 2% for every $10 - so price decrease was 6%.
Customer's price is currently $100.
We say - $100/1.06= new price of $94.3
Customer says - $100*.94= new price of $94.

They don't understand that if board went back up $30 which would be 6% increase, they wouldn't be back at $100 if they multiplied on the price decrease.
$94*1.06=$99.64 vs. $94.3*1.06=$100 (Back to the original price)

What is the best way to explain to customer besides using this example?

Any help or info is appreciated.

Craig
Victoria West lui répond.

Arithmetic Sum & Sequence 2009-09-01

Alice pose la question :
Find the 24th term of this sequence 6.8,8.0,9.2... Find the sum of the first 21 terms
Janice Cotcher lui répond.

Cardinality of infinite sets 2009-09-01

Brian pose la question :
I was reading an answer to a question on your site regarding infinite sets (http://mathcentral.uregina.ca/QQ/database/QQ.09.01/carlos1.html), and I think they may have got the answer wrong.

I his example, he claims that the set of real numbers BETWEEN 0 AND 1 is larger than the set of positive integers.

Please correct me if I am wrong, but I believe those two sets are -- pardon the expression -- equally infinite. For any integer, there is a corresponding real number between 0 and 1, and vice versa.

For instance, using the decimal as a "mirror", you can create a mirror image of any real number between 0 and 1 as an integer (i.e. 0.1234 gets mirrored as the integer 4321 -- I could write it out algebraically, if you want, but you get my point)

Am I wrong?

Thanks, Brian
Victoria West lui répond.

Sequence problem 2009-08-18

James pose la question :
I have the equation: t_n = (n)(n+1)/2 Which gives the sequence: 1, 3, 6, 10, 15 etc. However, I'd like to be able to solve for n. So that a t of 6 would give me the answer of 3, and t of 10 would give me the answer 4 etc.
Stephen La Rocque and Victoria West lui répond.

Subtraction base 5 2009-08-09

Nikki pose la question :
can you help me how to do subtraction in base 5 notation. example is 3434 - 51? how do you do this in base 5?
can you please explain how you do this & the answer as i have no idea.

Thank you kindly
Nikki
Harley Weston lui répond.

An infinite set 2009-08-07

Islam pose la question :
How can I prove that the set of all odd natural numbers is an infinite set. Thank you.
Robert Dawson lui répond.

Percentage decrease 2009-08-04

Bill pose la question :
How to calculate the Percentage Increase or Decrease of a $ value.
Example -
Site Spend for 01-01-2008 thru 07-31-08 was $ 3,465,660
Site Spend, 2009 YTD as of 07-31-09, was $ 1,673,405
Site Spend down what % between these two amounts ?
Penny Nom lui répond.

Angular speed 2009-08-04

Mary pose la question :
The engine of a sports car rotates at 5000 revolutions per minute (rpm). Calculate the angular speed of the engine in radians per second. Use 2 radians = 1 revolution.
Penny Nom lui répond.

Intersection of Two Curves 2009-07-27

Amarah pose la question :
Find the coordinates of the point A( this point is where the two lines intersect). Justify answer question : here is a curve x^y =y^x (for x,y>o)
Janice Cotcher lui répond.

How can I trisect an angle? 2009-07-27

Nazrul pose la question :
How can I trisect an angle?
Robert Dawson lui répond.

The inverse of F(x)=x^2-6x+13, for x>3 2009-07-26

Juan pose la question :
The function F is given by F(x)=x^2-6x+13, for x>3.

A. Write F(x) in the form (x-a)^2+b

B.Find the inverse function F^-1

C.State the domain of F^-1
Penny Nom lui répond.

Finding the Common Difference and Number of Terms of an Arithmetic Sequence 2009-07-24

Juan pose la question :
In an arithmetic sequence, the first term is -2, the fourth term is 16 and the nth term is 11,998 A. What is the common difference? B. What is the value of n.
Janice Cotcher lui répond.

A sundial on an elliptical cylinder 2009-07-22

Leo pose la question :
I want to build a sundial where the shadow falls on an elliptical cylinder. I can calculate the coordinates of the points on the cylinder that I want to mark. My problem is that I will have to make the surface as a flat sheet and bend it into an elliptical shape. However, I cannot work out a scheme to transfer the coordinates I know into a distance that will work when I bend the shape. Help!
Robert Dawson lui répond.

Annular sector 2009-07-20

Ed pose la question :
What is the name for the section of a flat ring (annulus)? Similar to a section on a radar screen, a quadrilateral but the top and bottom are curved.
Robert Dawson lui répond.

Finding the Line Joining Perpendicular Feet 2009-07-16

mukulu pose la question :
Please help I've been tryng to search in your data but i failed to get the solution Find the equation of a straight line joining the feet of the perpendiculars drawn from the point A(1,1) to the line 3x-3y-4= 0 and 3x+y-6=0.
Janice Cotcher lui répond.

A sequence 2009-07-11

jamie pose la question :
what is the next number in the sequence and what is the relationship of the numbers? 36,16,20,10,12, _
Penny Nom lui répond.

A base 7 number and a base 9 number 2009-07-09

koteawarao pose la question :
Find a base 7 three-digit number which has its digits reversed when expressed in base 9.

ans: (281) base 7 and (182) base 9
Harley Weston lui répond.

A binary equation 2009-07-07

Chinonyerem pose la question :
Find a bitwise solution (i.e find xi so that each xi E {0,1}) to
32 = x1 + 2x2 + 4x3 + 9x3 + 20x5
Harley Weston lui répond.

The retail price for an ice cream scoop 2009-07-05

Patricia pose la question :
Hi - I am trying to figure out the fairest retail price for an ice cream scoop. We have an ice cream parlor and the cost of the ice cream we buy by the bulk container has recently been increased so now we must charge more for our scoops. We pay a wholesale price of $25.40 for 242 ounces of ice cream. The cost per ounce is $0.105. What is the formula for figuring out how much to charge retail per scoop? This is probably so simple but confusing to me. Please help. Thank you!
Harley Weston lui répond.

Prove that the set of all positive odd integers is an infinite set 2009-06-20

Nazrul pose la question :
How can I prove that the set of all positive odd integers is an infinite set.
Thank you in advance.
Victoria West lui répond.

Successive differences 2009-06-18

Jonathan pose la question :
I'm trying to find the next number sequence for this equation: 1 11 35 79 149 251, my problem is that I worked it out and ended up with a single number 17. What am I doing wrong. Thank you for any help.
Robert Dawson and Penny Nom lui répond.

Subsets 2009-06-16

Tracy pose la question :
Suppose C is the subset of D and D is the subset of C.

If n(c)=5, find n(D)

What other relationship exists between sets C and D?
Penny Nom lui répond.

Two ships and a lighthouse 2009-05-27

Chelsey pose la question :
I have a question in regards to how do I know when to use tangent or cosine when determining angles. The question is: Looking north from the observation deck of a lighthouse 60 m above the sea, a lighthouse keeper sees two ships. The angles of depression to the ships is 5 degrees and 10 degrees. How far apart are the ships?

I don't understand which one to use when solving the equation.
Harley Weston lui répond.

A sequence 2009-05-26

Jay pose la question :
what is the equation that would give me the next 3 numbers in this progession: 0,1,5,14,20
Stephen La Rocque lui répond.

What type of conic section is this? 2009-05-22

Donna pose la question :
What type of conic section is 3x² + 3y² - 4y - 8 = 0
Penny Nom lui répond.

An infinite geometric series 2009-05-18

terri pose la question :
find the sum of the infinite geometric series

14 -7 +7/2 -7/4 +.....

A. 7007/13 B. 2002 C. 28/3 D.5005/7
Stephen La Rocque lui répond.

A sequence 2009-05-18

Richard pose la question :
This is my question about sequences. Write down the nth term of the following sequences.

1/2, -3/4, 9/8, -27/16

Plz help me solve the question!
Penny Nom lui répond.

A number sequence 2009-05-08

alicia pose la question :
what is the next number 1,2,6,42,1806------? is it 1954?
Robert Dawson, Chris Fisher, Penny Nom and Claude Tardif lui répond.

How do you convert 1248 to base 6? 2009-05-02

Tamara pose la question :
How do you convert 1248 to base 6?
Penny Nom lui répond.

Stairway construction 2009-05-02

Olivia pose la question :
Hi, I'm Olivia and I'm in 8th grade studying algebra 1. I'm having some trouble with my math project. It has to do with rules of stairway construction. It says that there are two generally accepted rules to building stairs. Rule 1: x+y=43 and x+y=46 (cm) Rule 2: 2y+x=61 and 2y+x=64 (y is the riser and x is the tread length) I cant figure out how to graph them...it says they're supposed to intersect to make a square which is like the safety zone for building stairs (the stairs' rise and tread lengths are plotted as points) any points outside of that square are considered unsafe. Did i explain it ok? Thanks for your help. --olivia
Penny Nom lui répond.

2+6+12+20+30+42 2009-04-24

fredy pose la question :
what is the sigma notation for the series 2+6+12+20+30+42?
Stephen La Rocque lui répond.

Miles per hour and feet per second 2009-04-22

mary pose la question :
A car traveling at 60 miles per hour, how many feet per second has it traveled?
Robert Dawson lui répond.

Percent increase from a negative number to a positive number 2009-04-21

Brian pose la question :
I have no problem calculating year over year net profits but am having trouble when it comes to a negative.
2007 Net Profit = -110,333.00
2008 Net Profit = 66,054.00

Brian
Harley Weston lui répond.

The center of an ellipse 2009-04-21

Nae pose la question :
what is the ellipse center of 5x^2+3y^2=15
Stephen La Rocque lui répond.

$65.09 is 70% greater than the average price 2009-04-11

Kelly pose la question :
Hello! I know you might be thinking that I didn't look through your previous answers, but I really did. Here's my dilemma- I have a percent increase equation that is missing the 'old" value. I know that $65.09 is 70% greater than the average price, but I do not know the average price. How do I go about finding that? I tried to set up an equation, but its throwing me off because the unknown variable is in there twice, and it's been a long time since I've taken math
Thank you for your help...greatly!
Penny Nom lui répond.

The axiom of choice and constructibe sets 2009-04-10

sydney pose la question :
The axiom of choice asserts the existence of certain sets, but does not construct the set. What does "construct" mean here? For example, does it require showing the existence and uniqueness of some function yielding the set? In general, what does it mean to require the existence of a mathematical object be tied to a construction of it?
Claude Tardif lui répond.

Direct and inverse relationships 2009-04-06

allison pose la question :
A piece of string is cut into n pieces of equal lengths L (1) does n vary directly or inversely with L
Penny Nom lui répond.

Three consecutive odd integers 2009-04-02

Brian pose la question :
Find the greatest of three consecutive odd integers if the product of the second and third is 8 more than 13 times the first.
Robert Dawson lui répond.

A 25 team league 2009-03-31

brad pose la question :
25 teams are in a league in which each team plays everybody once how many games must be scheduled ?
Penny Nom lui répond.

Adding in base six 2009-03-29

Lucy pose la question :
If you are working in base 6, what do you have to add to 4(base 6) to get 10(base 6)????
Penny Nom lui répond.

Uses of Pythagorean theory 2009-03-27

Britta pose la question :
Please, give me some complex real life situation examples where the pythagorean theory is used. It must be a grade 8 or grade 9 level of thinking as that is what is my teacher's demands.
Robert Dawson lui répond.

The base of a triangle 2009-03-25

yinna pose la question :
how do I find the base of a triangle who's height is 2 times the base and the area is 9?
Penny Nom lui répond.

The base and height of an isosceles triangle 2009-03-23

Chris pose la question :
How do you find the base and height of an isosceles triangle that has 2cm legs?
Harley Weston lui répond.

An equation for a line with a changing slope 2009-03-21

Ben pose la question :
Is there anyway to write an equation for a line with a changing slope. e.g. A cell [hone company has a initial fee of 50$ paying for the first 100 minutes, the rate then increases to 10 cents per minute, then at 500 minutes the rate is 5 cents per minute.

If so please tell how.
Thanks
Penny Nom lui répond.

A plane cuts a line segment 2009-03-17

Manis pose la question :
Find the ratio in which the line joining (2,4,16) and (3,5,-4) is divided by the plane 2x-3y+z+6=0.
Robert Dawson lui répond.

License plates and poker hands 2009-03-14

CC pose la question :
You have a license plate it can have 6 numbers/letters you can use the numerals 0-9 and the letters A-Z how many combos are possible and how did you figure it out?

Question 2,

Your dealt an Omaha hand You have KKKQQ, how many different hands can consist of the same cards.
Harley Weston lui répond.

A sequence 2009-03-13

Shelly pose la question :
Which sequence satisfies the rule n/4?
Stephen La Rocque lui répond.

Three consecutive odd integers 2009-03-11

Susan pose la question :
Find three consecutive odd integers such that the sum of the first, twice the second, and three times the third is 70
Penny Nom lui répond.

A sequence 2009-03-11

Vly pose la question :
2; 6; 26;126;626 find the nth term
Harley Weston lui répond.

The angles of a triangle 2009-03-11

Marissa pose la question :
The angles in a triangle measure 7x-1, 18x+2, and 5x+10. Determine whether the triangle is acute, obtuse, or right. State your reasons clearly.
Robert Dawson lui répond.

Trifecta 2009-03-09

Annie pose la question :
I want to know how many combinations are there for the first 3 horses in a race of 20 horses. For example, the horses can come in 1, 5, 7 or 7, 5, 1 which are totally different combos. I've only found formulas where the 1, 2, 3 and 3, 2, 1 are counted as the same combo. In horse racing every combo is different. Thank you.
Penny Nom lui répond.

A property that decreases in value every year by 10 percent 2009-03-07

PEter pose la question :
there is a competition problem where a cottage is worth 25000 years, but it decreases in value every year by 10 percent. Without a calculator, is there a way to find after how many years, the cottage will be worth 2500? (besides multiplying it out and besides logs)
Stephen La Rocque lui répond.

The ratio test 2009-03-06

Haley pose la question :
Use the ratio test to determine whether the series in convergent or divergent. (2/5)+(4/10)+(8/15)+...
Harley Weston lui répond.

Infinite sets and infinite limits 2009-03-06

Justin pose la question :
Hello, I know I have asked a similar question before but I was just wondering if set theory applies to the lim x->0, y=1/x=infinity and if so, what type of infinity would it be? Thanks a lot for your help with this question!

Regards,

Justin
Robert Dawson and Harley Weston lui répond.

Direct, inverse and indirect proportionality 2009-03-04

Brian pose la question :
My 14 year old is confused about indirectly proportional and inversely proportional. On searching on the internet we were directed to: http://mathcentral.uregina.ca/QQ/database/QQ.09.00/ellis1.html Here leanne starts explaining indirectly proportional and ends up describing inversely proportional. Has Leanne got it wrong ?
What is indirectly proportional.

Thanks
Brian
Chris Fisher lui répond.

Convergent or divergent? 2009-03-03

Betsy pose la question :
Use the ratio test to determine if the series is convergent or divergent. 1+1/2^2+1/3^3+1/4^4

I know the general terms are a(n)=1/n^n and a(n+1)=1/(n+1)^(n+1) but I can't simplify r=lim(n->inf.)=n^n/(n+1)^(n+1)
Robert Dawson lui répond.

An array with 2 more rows than columns 2009-02-28

Mario pose la question :
Write a division sentence modeled by an array that has 2 more rows than the number in each row.
Penny Nom lui répond.

Where do X, Y and Z go? 2009-02-27

Aj pose la question :
A E F H I K L M N T V W
B C D G J O P Q R S U

where do X, Y and Z go?
Robert Dawson lui répond.

1 3 6 10 15.... 2009-02-26

Allie pose la question :
1 3 6 10 15.... i know the pattern is +2 +3 +4 +5 and so on...but i dont know how to write an equation to find the nth term. help!
Robert Dawson and Claude Tardif lui répond.

Multiplying in different bases 2009-02-25

Susan pose la question :
11 base 2 X 22 base 3 + 33 base 4 = _________ base 5
Robert Dawson lui répond.

wo consecutive numbers with a product of 9506 2009-02-25

sofie pose la question :
find two consecutive numbers with a product of 9506
Penny Nom lui répond.

Pressure at Given Depth 2009-02-22

Tamara pose la question :
A sea is 3km deep. The average density of sea water there is 1020 kg/m^3. What is the water pressure at the bottom?
Janice Cotcher lui répond.

One vertex angle of a regular octagon is trisected 2009-02-19

Chelsy pose la question :
Suppose one vertex angle of a regular octagon is trisected as shown in the figure. Each side of the octagon measures 4 units. Find the area of the shaded area.
Robert Dawson lui répond.

The volume of a cylinder 2009-02-18

jim pose la question :
given the volume of a cylinder at 565m^3 and the height of 20m how do i calculate the cross section area in order to determine the compression strength of the cylinder
Harley Weston lui répond.

More on infinity and Set Theory 2009-02-17

Justin pose la question :
I greatly appreciate your help I was just wondering from your previous answer, why doesn't Cantor's cardinal numbers in set theory apply to the limit x->0, y=infinity?

Justin
Robert Dawson lui répond.

Miles per hour to kilometers per second 2009-02-17

Tamara pose la question :
If a car goes 60 miles in an hour how many kilometres will it go in a second?
Penny Nom lui répond.

Infinity and Set Theory 2009-02-17

Justin pose la question :
I was just wondering is the limit x->0, y=1/x=infinity, the biggest uncountable infinity according to Cantor's cardinal numbers in set theory?

Justin
Robert Dawson lui répond.

The second derivative of h(x)=f(g(x)) 2009-02-16

Kristina pose la question :
If h(x)=f(g(x)), and is differentiable, then find h"(x).
Robert Dawson lui répond.

In what base is 3x3= 10? 2009-02-14

David pose la question :
In what base is 3x3= 10, 3x3=11, 3x3 = 12? is there a fast way to see this or do I have to create multiplication tables until I find the right one?
Penny Nom lui répond.

y = p q^t 2009-02-12

Conor pose la question :
y= p x (q (to the power t) ) ; y= 100 when t = 2 and y= 4 when t= 0

a) find p and q
b) hence find y when t=4
Stephen La Rocque lui répond.

A semi circular room 2009-02-11

Taylor pose la question :
being 450pi (the area of a semi circle)

how much money would it cost to lay carpet at $2.57 per foot???

if the area of a semi circular room is 450 pi ft then what is the volume being that the diameter is 60 feet and the ceiling is 16 feet tall
Robert Dawson and Penny Nom lui répond.

Seating around a circular table 2009-02-09

Jenny pose la question :
A committee of 15 -- 9 women and 6 men -- is to be seated at a circular table (with 15 seats). In how many ways can the seats be assigned so that no two men are seated next to each other?
Victoria West lui répond.

Congruent line segments 2009-02-05

casie pose la question :
marica drew one-line segment on a graph with endpoint of (0,9) and (0,4). she drew another line segment with endpoints (1,1) and (6,1). are the line segment congruent?explain
Penny Nom lui répond.

The sequence 5, 12, 19, 26, ... 2009-02-04

Vickie pose la question :
Hello, Here's the question. Ryan wanted to play basketball on a team, He started practicing shooting everyday to improve his skills. The first day he make 5 shots, the second day he made 12 shots, the third day he made 19 shots, and the fourth day he makde 26 shots. If the first day was March 1 and the pattern continues, how many shots will Ryan make on the last day of April and the last day of July? My daughter's answers were 425 for April and 1069 for July. Are these correct and what would be the formula for this question? ? +N=? I don't know please help. Thank you, Vickie
Robert Dawson and Penny Nom lui répond.

A piecewise function for monthly salary 2009-02-03

Josh pose la question :
A sales rep for a drug company is paid on the following scale. His base salary is $1600 per month. He is also paid a commission of 2% of sales over $20,000. When his gross sales reach $30,000 he is then paid 4% on the amount above that until his sales reach $50,000 after which point his commission becomes 6%. His commission reaches 8% when his sales total goes over $100,000 for the month. Set up a piecewise function for the information above.
Harley Weston lui répond.

Calculating markup 2009-02-03

Tonya pose la question :
I'm trying to figure out the formula for the following, I have a product that I want to receive a certain profit, but with this product I also have to pay a percentage of commission to someone. I need to know how to calculate my new selling price taking into account the markup percentage, but I don't want my cut to be lowered. I have calculated the markup percentage to get my new selling price with the commission, but it lowers my cut once I pay the commission and I don't want it to do that. Thanks
Penny Nom lui répond.

What do I need to pass the course? 2009-02-02

Lynnette pose la question :
If I received 100% on my assignment which is worth 20% of my total mark and 87% on my midterm which is worth 40% of my total mark what would I need to get on the final exam which is worth 40% of my mark. To pass the course I must have 80% or above. Thanks.
Penny Nom lui répond.

The sequence 2n! - 1 2009-02-01

Penny pose la question :
I am trying to help my son with this problem. Find the first five terms of the sequence that can be written from the formula A= 2n !-1.
Penny Nom lui répond.

The intersection of two lines 2009-01-30

kaylee pose la question :
how do you find and graph the intersect of these two equations: y=2x-4 (and) 2y=x thanks, kaylee
Stephen La Rocque lui répond.

Ambitious 7th Grader 2009-01-28

John pose la question :
I have been asked to tutor a 7th grader who is very good in math. He is taking the most advanced course that his school offers to 7th graders. This course will cover Algebra 1 over a period of two years, using McDougal Littell's Algebra, Structure and Method, Book 1, a book I like a lot.

I have been hired not to help him with his schoolwork, which is too easy for him, but to guide him through something in math beyond his schoolwork. This was his idea, an idea which surprised his parents, but one which they support.

Do you have a suggestion for me? If so, I would be very grateful to hear from you. I think this could be a lot of fun for me and my new student, if I pick the right path.

Thanks and best regards, John John
Robert Dawson, Victoria West and Walter Whiteley lui répond.

Percentage increase 2009-01-19

Destiny pose la question :
In 1990 there were 25 springs in the park. This year there are 35 springs in the park. What is the percent increase?
Penny lui répond.

The point of intersection of the straight lines 2009-01-18

Kieran pose la question :
Find the point of intersection of the straight lines

y=2x+4, and y+2x-16=0
Robert Dawson and Penny Nom lui répond.

Segments of a sphere 2009-01-16

Herman pose la question :
How do I solve for a segment of a sphere so that the orange peel or pie shaped section is converted to a flat surface with dimensions. I form large diameter domes, elliptical and sphere heads on a press. I enter the diameter say 30 feet with two segments above and below the equator and the total number of segment around the circumference at say 18 so the widest part of the pie shaped section will fit my press. How do I take the upper or lower course above or below the equator and figure the height of the orange peel shape, the chord length at top and bottom, and solve for the right angle at 2 degree increments down the arc length of the pieces so I can layout the flat plates prior to pressing. Thanks for your help.
Robert Dawson lui répond.

A seven card poker hand 2009-01-12

Sean pose la question :
from a standard card deck, seven cards are chosen at random. find the probability that the set chosen contains exactly three of each of two different face values.

the second part of the problem asks the probability that the card hand contains exactly three 2's and exactly three 5's.
Robert Dawson lui répond.

(a x b) intersect (b x a) 2009-01-08

sean pose la question :
is it possible to have two sets such that n((a X b) intersect (b X a) =3
Harley Weston lui répond.

A union B and A intersect B 2009-01-07

Jim pose la question :
Suppose A and B are sets and (A union B) = (A intersect B). Is it true that A=B.
Penny Nom lui répond.

y varies jointly as x and the square of z and... 2009-01-05

peter pose la question :
I don't really get the terms in this problem. Could you explain it: If y varies jointly as x and the square of z and inversely as the cube of w, by what factor is y increased when z is doubled and w is divided by 3 and x remains the same?
Harley Weston lui répond.

The area enclosed by a curve and the x-axis 2009-01-04

Rogerson pose la question :
Find the area, S, enclosed by the curve y = -x^2 + 6x - 5 and the x-axis in the interval 0≤x≤4.
Harley Weston lui répond.

Determine y'' by implicitly differentiating twice 2009-01-04

Walter pose la question :
Given x^3 - 3xy + y^3 = 1 , determine y'' by implicitly differentiating twice. I cannot solve this. Would you be kind enough to perform the mathematics and show the steps involved in obtaining the solution?
Harley Weston lui répond.

What is f^-1(3) when f(x)=2x-1? 2009-01-03

Peter pose la question :
how do you do functions like f^-1(3) when f(x)=2x-1?
Penny Nom lui répond.

Jon's bank account 2009-01-03

Abigail pose la question :
Hi, i have an exam soon (monday =[ ) in my revison book, it shows two peoples bank accounts- and then it says

"write a formula to show the balence of Jon's bank account after n weeks of 2003" this is the table show

Jon's Bank account

Weeks Week 1 Week 2 Week 3 Week 4 Week 5

Balance(£) 970 1035 1100 1165 1230

Penny Nom lui répond.

A spill of oil on a flat surface 2008-12-19

Phillip pose la question :
Hello, my question is: If I spilled 25 gallons of diesel fuel on a flat surface how much area would the spill cover? How would I mathematically figure it out? Thanks!
Robert Dawson and Harley Weston lui répond.

The inverse function for F(x)=x^3+x 2008-12-18

alireza pose la question :
I want inverse function for F(x)=x^3+x
Robert Dawson lui répond.

The middle term of an arithmetic sequence 2008-12-15

Leigh pose la question :
Find the sum of the first fifteen terms of an arithmetic series if the middle term is 92
Penny Nom lui répond.

Annual percent growth 2008-12-13

Joe pose la question :
If Wall-Mart had sales of $58,200,000,000 in the year 2002 and $90,800,000,000 in the year 2006.

1. Find what percent that increase is of the 2002 sales? I came up with (9.08*10^10 - 5.82*10^10) / 5.82*10^10 * 100 = 56.01% increase. Is this correct?

2. What was the percent GROWTH in Wal-Mart's sales from 2002-2006? I am having trouble figuring out how to do the Growth problem. I would appreciate any help.
Harley Weston lui répond.

The third vertex of a right triangle 2008-12-10

prashant pose la question :
how to calculate coordinates of third vertex in a right angle triangle given the coordinates of hypotenuse as (1,3) and (-4,1)
Robert Dawson lui répond.

Division in different bases 2008-12-02

MICHELLE pose la question :
DIVIDE 538 BY 14 IN BASE 2, 3, 4 & 5
Penny lui répond.

A log base 2 problem 2008-11-26

dave pose la question :
solve for x

(log base 2 of x) - (log base 2 of (x-2)) = 3
Penny Nom lui répond.

Sec(2x) 2008-11-23

Evan pose la question :
Prove that this is an identity...

sec2x = sec^2x / 2 - sec^2x
Harley Weston lui répond.

The nth term of a sequence 2008-11-20

kim pose la question :
Find the next 2 terms of the sequence.
11n+2.5
Harley Weston lui répond.

The height, base and perimeter of a triangle 2008-11-17

Zack pose la question :
How would i calculate the height of a triangle if the base is 10cm and the area is 50cm²? If possible how would i calculate the length around the the triangle.
Penny Nom lui répond.

License plates 2008-11-17

Clayton pose la question :
Okay, so in this situation a license plate must have four letters (A-Z) and four numbers (0-9), ex. ABCD-1234, where repeating a letter or number is allowed ex. AAAA-1234, or ABCD-1111, or AAAA-1111. The order of letters first numbers second, or number first, letters second is allowable, and each state has its own plates, so ABCD-1234 from New York, and ABCD-1234 from Minnesota are considered different combinations, how many different license plates could there be?
Penny Nom lui répond.

The nth term of a sequence 2008-11-16

Robin pose la question :
How do I solve for the next term in the following sequence, I just don't want the answer...I want how to do it to. x,x -1, x -2

Also, how do I solve for the nth term? I can't understand the explanations I've found. He has numbers subscripted in his equations.
Victoria West lui répond.

The midpoint o a line segment 2008-11-15

Jane pose la question :
The vertices of a triangle are at (1,7), (6,-1) and (0,3). Find the coordinates of the midpoints of the sides.
Penny Nom lui répond.

A cross-sectional area 2008-11-13

David pose la question :
I am doing a science project examining the tensile strength of seaweed fronds. I need to calculate the cross-sectional area from the major and minor diameters of the elliptical central axis of the seaweed frond. What formula would I use to get this. The strength of the segments is expressed in terms of cross-sectional area of the frond at the test site.
Penny Nom lui répond.

1/8, 2/7, 1/2, 4/5, ..., ... 2008-11-06

katie pose la question :
Inductive reasoning, what 1/8, 2/7, 1/2, 4/5, what would be the next two in th sequence.
Penny Nom lui répond.

An arch is in the form of a semi ellipse 2008-11-03

jessica pose la question :
An arch in the form of a semi ellipse has a span of 10 meters and a central height of 4 m. Find the heights of the arch at a point of 3 meters from the semi minor axis.
Penny Nom lui répond.

A sequence 2008-10-26

Nicole pose la question :
what is the rule to this sequence 3,6,12,24,48.....
Penny Nom lui répond.

The sequence 49,48,46,43,39... 2008-10-26

Kyle pose la question :
What number comes next in the series 49,48,46,43,39...?
Stephen La Rocque lui répond.

The sequence 6,1,6,2,6,4,6,8,6, 2008-10-26

Kyle pose la question :
What number comes next in the series 6,1,6,2,6,4,6,8,6,?
Stephen La Rocque lui répond.

The amount of diesel fuel in a tank 2008-10-26

Mike pose la question :
I have an cylinder shaped oil tank that holds approx. 283 gals of diesel fuel. The tank is laying on on its side, (like taking a garbage can and laying it down on its side). What is the formula to calculate how much oil is in the tank at any given time. If the tank was sitting on end it would be easy to figure out, but it is not.
Stephen La Rocque lui répond.

nth term 2008-10-22

jen pose la question :
what is a nth term and how do i find the nth term of any sequence
Penny Nom lui répond.

A canal with cross section a semicircle 2008-10-19

Connor pose la question :
a canal with cross section a semicircle is 10m deep at the centre. Find an equation for the semicircle and use it to find the depth 4m from the edge
Penny Nom lui répond.

An arithmetic series 2008-10-17

Laura pose la question :
In an arithmetic series 5+9+13+...+tn has a sum of 945. How many terms does the series have? What formula do I use?
Penny Nom lui répond.

Bags of wheat seed 2008-10-16

Gayle pose la question :
If you want to plant 26 seed per square foot (wheat) on one acre of land and the seed comes in 50 lb bags and there are 13,500 seed per pound (675,000) per 50 pounds, how many bags do you need to plant per acre?
Penny Nom lui répond.

Bags of pennies 2008-10-11

paul pose la question :
jenny divided 15 pennies among 4 money bags.she could then pay any amount from 1p to 15p just by giving bags.how many pennies did jenny put in each bag?
Penny Nom and Victoria West lui répond.

The volume of fluid in a semi circular trough 2008-10-10

Kerry pose la question :
How do I find the volume of fluid in a semi circular trough?
Penny Nom lui répond.

A 10% increase in supply 2008-10-10

Irena pose la question :
How do you find begining inventory if after 10% increase in supply you got 27.5 units
Penny Nom lui répond.

Three consecutive integers 2008-10-07

pam pose la question :
Find three consecutive integers such that the greatest increased by twice the least is 293.
Penny Nom & Chris Fisher lui répond.

The rise over the run 2008-10-07

Mak pose la question :
what is the ratio of the rise to run?
Penny Nom lui répond.

Area of a semicircle 2008-10-06

Benjamin pose la question :
How do you find the area of a semi-circle if the diameter is a variable.
Penny Nom lui répond.

Does an oval have sides? 2008-10-02

reid pose la question :
My 6 yo neice came home with her math homework and she was supposed to identify which objects had sides.One of the objects was an oval.I don't believe it has sides because it is curved and I don't think that would make it an object with sides.What would be the correct answer?Thanks,Reid
Janice Cotcher lui répond.

The empty set 2008-09-29

wahab pose la question :
Why a null set is called a set? the definition of set includes that a set is a collection of well defined objects But a null set is having no value.
Harley Weston lui répond.

The nth term 2008-09-29

shauna pose la question :
The first five numbers in a sequence are
40, 37 34, 31, 28
Find an expression for the nth number in the sequence.
Penny Nom lui répond.

3,6,10,15,and 21 2008-09-28

jarred pose la question :
i am currently stumped on a math project that requires me to find out the recursive formula for a sequence of numbers. the numbers in the sequence are 3,6,10,15,and 21. Thank you for your time.
Walter Whiteley lui répond.

The area of an arched transom 2008-09-28

Ivan pose la question :
What is the formula for figuring out the square footage of arched transom windows & doors?
Harley Weston lui répond.

Increase pricing by 5% 2008-09-28

Adrian pose la question :
I am working to increase pricing by 5%. If the price is 100, I would typically use the formulas 100 * 1.05 = 105, which is a $5 increase. An associate suggests I divide to get the desired increase. For example, using $100 with a 5 percent increase. I would use the forumula 100/.95 = 105.26. Thas is a 5.26 increase. Can you explain this method to me an why the different increases? Which one is correct.
Penny Nom lui répond.

Two consecutive numbers 2008-09-21

tomas pose la question :
what is the two consecutive numbers with a product of 4160?
Penny Nom lui répond.

The area of a garden 2008-09-20

Hannah pose la question :
How do you find the area of a semi circle when no measurement is given? The question is find the area of the garden which is semi circular. The measurements are 24m and 26m and the semi circle's height is 10m!
Penny Nom lui répond.

Finding the Pattern in a Sequence 2008-09-16

sjp pose la question :
please could you help me find the nth term for 8 4 0 -4 -8 and -4 -1 4 11 20 Thank you
Janice Cotcher lui répond.

The nth term of a sequence 2008-09-13

lavett pose la question :
what is the Nth term in the sequence when the sequence is 2,4,8,16... and the term numbers are 1,2,3,4...
Stephen La Rocque lui répond.

The height and base of a triangle 2008-09-12

Bailey pose la question :
The length of the base of a triangle is 1cm less than 5 times the height of the triangle. The area of the triangle is 21 square cm. What is the the height of the triangle and the length of the base of the triangle?
Stephen La Rocque lui répond.

0.151515...=15/99 2008-09-08

Emma pose la question :
This week, my Algebra teacher told us about the pattern between infinitely repeating decimals and their corresponding fractions. (ex. .2222222...= 2/9, .151515...=15/99, 456456456...=456/999, etc.) I was just wondering the reason why this pattern occurs. Is there a certain element that causes this pattern to occur?
Thanks
-Emma
Penny Nom lui répond.

An exclusion zone around a triangle 2008-09-07

Awrongo pose la question :
A long time ago Mr Gibson found an island shaped as a triangle with three straight shores of length 3 km,4 km and 5 km. He declared an 'exclusion zone' around his island and forbade anyone to come within 1 km of his shore. What was the area of his exclusion zone?
Stephen La Rocque and Penny Nom lui répond.

A security camera 2008-09-07

Rita pose la question :
A security camera in a neighborhhod carnival is mounted on a wall 9 feet above the floor inside a video gallery. What angle of depression should be used if the camera is to be directed to a spot 6 feet above the floor and 12 feet from the wall?
Stephen La Rocque and Harley Weston lui répond.

The selling price 2008-09-04

Robert pose la question :
Client wants to sell his property providing he is left with 100000.00$ net. How do I calculate selling price if commission is 6% and taxes on the commission 6% Fed and 7.5%prov. I'm taking the real estate class and this one really got me.
Penny Nom lui répond.

Half a circle 2008-09-04

brandon pose la question :
what are the area and perimeter and area of half a circle??
Penny Nom lui répond.

Aboriginal number groupings 2008-09-04

Barbara pose la question :
Our current place value system is based on the notion of 10s. Did Aborginal people use a similar system or did they group numbers differently?
Harley Weston lui répond.

Four weights 2008-08-25

Darla pose la question :
A balance had known weights of 1/2 lb, 1/4 lb, 1/8 lb, and 1 oz. Edna's object weighted 2 oz. more than Paul's. Each used 3 known weights to weight his or her object. which know weights did each use?
Penny Nom lui répond.

Eccentricity of an Elliptical Orbit 2008-08-20

Gina pose la question :
A satellite has an elliptical orbit around the earth with one focus at the earth’s center, E. The earth’s radius is 4,000 miles. The highest point that the satellite is from the surface of the earth is 800 miles, and the lowest is 200 miles. What is the eccentricity of the satellite’s orbit?
Janice Cotcher lui répond.

The intersection of the medians 2008-08-18

Katie pose la question :
Q: A Triangle is positioned with one side on the x-axis, the coordinates for the triangle are (-a,0), (a,0), (b,c)

a) Find the coordinates of the point of intersection of the perpendicular bisectors of the sides
b) Find the coordinates of the point of intersection of the medians
c) Find the coordinates of the point of intersection of the altitudes
Penny Nom lui répond.

A 3% increase 2008-08-18

RENEE pose la question :
I need to know how to do a 3 percent increase for $118,200......x's it by 3% will not work please answer fast
Penny Nom lui répond.

Graphing a piecewise function 2008-08-12

Shanti pose la question :
how do you graph a step function or piecewise function such as
u^2 if u is greater than or equal to -2 and less than 1
2- u if u is greater than or equal to 1 and less than 4
Penny Nom lui répond.

The base of a triangle 2008-08-10

Mark pose la question :
What is the formula I need to use to find the base of a triangle sail that is 16 feet high and has an area of 64 square feet.
Stephen La Rocque and Penny Nom lui répond.

Angles in a regular tetrahedron 2008-08-07

Carla pose la question :
Hi guys, A regular tetrahedron has all its edges 8cm in length. Find the angles which an edge makes with the base. Thanks. Carla
Penny Nom lui répond.

Arc-length and sector-angle 2008-08-06

Benson pose la question :
If chord length, radius are given, How to find the sector angle and arc-length
Janice Cotcher lui répond.

Cost of pencil is rising every year since 7 years ago 2008-08-06

Mari pose la question :
Cost of pencil is rising every year since 7 years ago. If the cost of pencil last year was 60 cents which is the sum of the cost from the last two previous years, what is the cost of the pencil now, the cost seven years ago.
Penny Nom lui répond.

Demographics 2008-07-25

shahrukh pose la question :
Each year for 10 years ,the population of a city increased by 5% of its value in the previous year. If the initial population was 200 000 ,what was the population after 10 years ??
Penny Nom lui répond.

The midpoints of the sides of a quadrilateral 2008-07-22

JOEL pose la question :
A QUADRILATERAL A,B,C,D HAS THE CO -ORDINATE [2,5],[8,7],[10,3]&[0,1] RESPECTIVLY [B,E,G,H] ARE THE MID POINTS OF THE SIDES AB,BC,CD&DA RESPECTIVLY FIND THE MID POINTS OF [FG]&[FH]
Penny Nom lui répond.

Taking two math classes 2008-07-21

Bailey pose la question :
i am going into the 7th grade, but i am going to be taking 9 th grade math. i was wondering if anyone could help survive doing two different math classes at the same time.
Harley Weston lui répond.

Three consecutive positive integers 2008-07-20

AC pose la question :
find three consecutive positive integers such that the product of the first and third, minus the second, is 1 more than 4 times the third
Penny Nom lui répond.

Choosing 5 numbers out of 39 numbers 2008-07-18

robert pose la question :
Please list the way I can choose 5 numbers out of 39 numbers, without repeating them, starting at number 1.

Please send me a list of all 120 combination.
Harley Weston lui répond.

Does the sequence 1 2 4 8 16 32 etc have a name? 2008-07-17

Richard pose la question :
Just an idle thought really. Does the simple sequence 1 2 4 8 16 32 etc have a name?
Victoria West lui répond.

1, 2, 4, 8, 16, 32 ... 2008-07-15

eve pose la question :
I have to find out the fomula for:

1, 2, 4, 8, 16, 32 ...
Penny Nom lui répond.

A reflected line segment 2008-07-14

Peter pose la question :
Segment AB has endpoints A(-1,2) and (3,1). Segment AB is reflected over the y-axis such that A becomes A' and B becomes B'. What is the positive difference between the lengths of segment AA' and segment BB'?
Janice Cotcher lui répond.

Choosing a number from 1 - 400 2008-07-04

Peter pose la question :
The numbers 1-400, inclusive, are put into a hat. What is the probability that the first number chosen at random is a multiple of 4 or 17? Express your answer as a common fraction. How do you do this the question without a calculator?
Leeanne Boehm lui répond.

A series solution of y' = xy 2008-07-03

sasha pose la question :
I've to find the power series solution of the differential equation: y' = xy.
I don't know how to find the recursive equation. Can you please help me. Thanks
Harley Weston lui répond.

Percentage increase 2008-06-29

Paul pose la question :
Could you please help me with this question. I was paying $98.00 a month for my health insurance premium, now it is up to $125.83 How much of an increase is that as a percentage increase, and how can I do this on a calculator. I'd like to know how much my increase is as a percentage.
Penny Nom lui répond.

A 7-digit odd number 2008-06-26

Godryk pose la question :
I am the smallest 7-digit odd number. my ones digit is the sum of my thousands, and ten thousands digits. What number am I?
Penny Nom lui répond.

Product of Two Integers 2008-06-25

devin pose la question :
two consecutive integer have a product of 240. what are they
Penny Nom lui répond.

How do you change bases? 2008-06-17

Peter pose la question :
How do you change bases eg. 121 from base 3 to base 5?
Penny Nom lui répond.

A piecewise equation 2008-06-16

John pose la question :
AT&T charges $39.99 for 450 minutes per month. It charges 45 cents per minute over the 450 minutes. How can I make a piecewise equation of this problem?
Penny Nom lui répond.

An ellipse and circle with the same area 2008-06-09

Michael pose la question :
The area of the ellipse if equal to the area of a circle with radius=40 ft. Find the values of a and b using appropriate algebraic techniques, not basic math computations. A=pi ab and satisfy the constraint a+b=100????
Penny Nom lui répond.

Geometric sequences 2008-06-08

Rita pose la question :
A geometric sequence is given. Find the common ratio and write out the first four terms.

(1) {(-5)^n}

(2) {(2^n)/(3^(n - 1)}
Penny Nom lui répond.

90% of gross leaseable footage 2008-06-07

Rosalind pose la question :
90% of gross leaseable footage in the shopping center, being 394,577, excluding that square footage leased by major anchor tenants, being 284,747. Would you deduct the 284,747 from the 394,577, then multiply by the 90%. Or would you multiply the 394,577 by the 90%, then deduct the 284,747?
Penny Nom lui répond.

A recursive formula for 9, -18, 36, -27, ... 2008-06-05

Rita pose la question :
I am having trouble understanding how to write formulas (I should say create formulas) from a given sequence. It does not matter what sort of sequence it is. The confusion remains. I have not found a textbook or easy math book that explains this process for the average Joe to grasp. Here are the two questions:

(1) Write a recursive formula for the sequence
9, -18, 36, -72, ...

(2) Write a recursive formula for the sequence
3, 3(sqrt{3}), 9, 9(sqrt{3})
Penny Nom lui répond.

The path of a baseball 2008-06-04

Tom pose la question :
How high would a batter have to hit a ball to clear the stadium roof in right field if the distance to the right field fence is 320 feet from home plate? Is this solvable?
Janice Cotcher lui répond.

Calculating a price based on markup 2008-06-03

Sheldon pose la question :
I know the most common form for retail businesses of calculating a price based on markup is: Cost/(1 - Markup), but how is this supposed to work for a business that desires a markup of over 100%.
Harley Weston lui répond.

Two consecutive negative even numbers 2008-06-03

Chelsea pose la question :
The sum of the squares of two consecutive negative even numbers is 100. Find the integers,
Penny Nom lui répond.

Inverse variation 2008-05-22

leria pose la question :
In Boyle's law, the pressure of gas varies inversely with the volume of the gas. A volume of 11.2 liters of air exerts a pressure of 2.0 atmospheres.

determine the constant of variation and write an equation the models the relationship between the pressure of the gas P and its volume, V. Use the equation to predict the volume of air necessary to exert a presure of 0.25 atmospheres.
Janice Cotcher lui répond.

How much seed do I need per plot? 2008-05-13

Jaye pose la question :
The plot size is 5 m X 2 m. The seeding rate is 12Kg/ha. How much seed do I need per plot? I have failed to get a proper answer. Thank you.
Penny Nom lui répond.

Selling price 2008-05-10

Roxane pose la question :
I'm trying to figure out the formula for the following, I have a product that I want to receive a certain profit margin, but with this product I also have to pay a percentage of commission to someone. I need to know how to calculate my new selling price taking into account the markup percentage, but I don't want my gross margin to be lowered. I have calculated the markup percentage to get my new selling price with the commission, but it lowers my profit margin once I pay the commission and I don't want it to do that.
Penny Nom lui répond.

The area of a sector of a circle 2008-05-10

lupio pose la question :
a problem asks for the area of a sector in a circle,no central angle,in circle is given only 5cm radius, three answers 180-90-35
can't find a way to start.Help
Harley Weston lui répond.

The inverse of a function 2008-05-03

keith pose la question :
please help me find the inverse of this function:

h(t) = 2 + 4 ln(1-5t)
Stephen La Rocque lui répond.

The standard form of an ellipse 2008-04-30

Rebecca pose la question :
I have to write the following equation into standard form of an ellipse:

9(X-1)^2 + (Y+1)^2 = 1
Stephen La Rocque and Harley Weston lui répond.

3-3+3-3+3.........up to infinite terms = ? 2008-04-25

Jatin pose la question :
3-3+3-3+3.........up to infinite terms = ?
Stephen La Rocque lui répond.

Two intersecting circles 2008-04-17

Muhammad pose la question :
Hi, how can we find the perimeter and area of the region common to two intersecting circles of radii 6 cm and 4 cm with centers 7 cm apart.
Harley Weston lui répond.

Conic sections 2008-04-14

Christine pose la question :
In my analysis class we are learning about conic sections. Our project is to create a genral statement of the definition of conic sections. Truthfully, I have absolutely no clue on how I should write that. Could you help me?
Walter Whiteley lui répond.

The maximum area of a pizza slice 2008-04-12

charles pose la question :
A slice of pizza in the form of a sector of a circle has a perimeter of 24 inches. what value for the radius of the pizza makes the slice largest[when o is the central angle in radians, the area of the sector is given by A= r^20/2and the length on the circle is given by s=r0
Harley Weston lui répond.

Two function problems 2008-04-10

keith pose la question :
find the domain: F(x)= 1/ {ln (x+5) - ln (7-x)}

find the inverse: g(t)= sqrt {2-3 ln (1-t)}
Penny Nom lui répond.

cosec [arccos (1/y)] 2008-04-09

Tom pose la question :
I am having trouble with this question. For y > 1, the value of cosec [arccos (1/y)] is?
Penny Nom lui répond.

1-(1-P)^75=0.05 2008-04-05

Amy pose la question :
1-(1-P)^75=0.05
Stephen La Rocque and Penny Nom lui répond.

Two consecutive odd integers 2008-03-24

Jarrod pose la question :
the sum of two consecutive odd integers is 24. Find the two integers
Stephen La Rocque lui répond.

Circles and semicircles 2008-03-23

sally pose la question :
Hi i am sally ,

i need to know what is the formula of :

Find perimeter and area of a semicircle ?

Find the area of a circle whose circumference ?
Penny Nom lui répond.

5 9 1 6 10 12 2, where does 3 fit in and why? 2008-03-22

Cassidy pose la question :
number sequence

5 9 1 6 10 12 2, where does 3 fit in and why?
Claude Tardif lui répond.

4,12,24,40,60,84 2008-03-18

kirsty pose la question :
Here are the first six terms of a sequence.

4,12,24,40,60,84

Find in terms of n, an expression for the nth term of teh sequence.
Stephen La Rocque lui répond.

Distance seen 2008-03-18

Nev pose la question :
formule: Distance Seen
S = 1.225 x square root of H
S = Distance seen in Miles
H = Height in Feet

What dose 1.225 Relate To ?
Stephen La Rocque lui répond.

The nth term 2008-03-16

ryan pose la question :
need help figuring nth term for 1, 2, 5, 14, 41...... could you please help
Penny Nom lui répond.

1, 1, 2, 3, 5, 8, 13, ___ ___ ___ 2008-03-13

Karen pose la question :
What is the rule for the following pattern, and what would come next?

1, 1, 2, 3, 5, 8, 13, ___ ___ ___
Penny Nom lui répond.

Inverses of functions 2008-03-13

jess pose la question :
if g(x)=2x+3 find g^-1(g(4)) how do I sovle I cant's figure out what to do with the 4
Stephen La Rocque lui répond.

Two consecutive odd positive integers 2008-03-12

Sarah pose la question :
The sum of the squares of two consecutive odd positive integers is 74. What are th integers?
Penny Nom lui répond.

Estimate the cube root of 270 2008-03-11

Tom pose la question :
(a) By plotting suitable graphs, estimate to one decimal place the cube root of 270.
(b) With reference to your answer to part (a), use 8 iterations of a Bisection Search to refine your estimate. Use the nearest whole numbers either side of your estimate from part (a) as starting values.
(c) Using either of your starting values from part (b) as first guess, use the Newton-Raphson method to find the true value of the root (to 6 decimal places). Repeat using the other starting value from part (b) and compare the two results.
Harley Weston lui répond.

Base 5 arithmetic 2008-03-06

Jana pose la question :
Hello, my name is Jana, i have asked a question here previously about how to count in base-5. I am happy now because i can convert any number now and it is very easy for me. The only thing i am having trouble with is understanding how to do a maths sum or times base-5 numbers. it is just a bit hard for me. So do you think you could explain how to do a sum in base-5 and how to do a multiplication sum. Please help...Thankyou Jana!!
Harley Weston lui répond.

What was the ostrich's speed in miles per hour? 2008-03-03

jacob pose la question :
If it took an ostrich 2.5 seconds to travel 110 feet and the average speed is 44 feet/ seconds, what was the ostrich's speed in miles per hour?
Penny Nom lui répond.

Convert from base 6 to base 12 2008-03-02

Jade pose la question :
I am trying to convert 13405 base 6 to a base 12 number. I am not allowed to go into a base 10 number. How will can I base 12 without doing anything with base 10? Thank you kindly.
Stephen La Rocque and Penny Nom lui répond.

The perimeter of a sector of a circle 2008-02-28

erica pose la question :
What is the perimeter of a sector if the radius is 18 and the middle arc is 150?
Penny Nom lui répond.

3 consecutive odd integers 2008-02-28

Pat pose la question :
For 3 consecutive odd integers, twice the first integer, plus 5 more than the second integer, plus three less than four times the third integer equals -85. Find the 3 consecutive odd integers.
Penny Nom lui répond.

The surface area of an ellipse 2008-02-25

paritosh pose la question :
how is the surface area of a elliptical dome be calculated when the two diameters are 55 metres and 35 metres and the height of the structure is 13.4 mts?
Harley Weston lui répond.

Counting in base 5 2008-02-24

Jana pose la question :
my name is Jana, i really need help with a maths question at school. Im confused about how to count up from1-20 in a base-5 format! I'm in year 5 and i really don't get all the complicated stuff.
Stephen La Rocque lui répond.

Actural cost, selling price and commission 2008-02-21

LiSa pose la question :
I have a question about a few things if anyone can answer... ex. actual cost (AC) = $1000 selling price (SP) = $ amount earned for company (C) = 15% of... selling price? commission 1 (C1) = 2.5% commission 2 (C2) = 2.5% How would you calculate how much the company's commission amount would be as well as the amounts for the other 2 that get 2.5%? And what would the selling price be? (the 15% $ + 2.5% $ + 2.5% $ ?) Is the 2.5% taken from the original amount? I am soooo confused! If anyone could help, that would be great!
Harley Weston lui répond.

Find the next terms 2008-02-20

Darrin pose la question :
I was given a number sequence and can't figure out the next terms to this

2,9,20,35,66,91......
Penny Nom lui répond.

Classifying a triangle 2008-02-07

kevin pose la question :
scalene triangle 8 ft base right side 9.5 left side 12 ft what is the angles
Penny Nom lui répond.

The perimeter of a semicircle 2008-02-02

Lisa pose la question :
How do you find the perimeter of a semi circle when you are only given the diameter, say 24 units?
Penny Nom lui répond.

Cross-sectional area of a fire hose 2008-01-27

Tom pose la question :
My question is this I know the equations for the final answer but the book skips how to get to one section of the equation. Q=(a)(v) A= The cross-sectional area of the conduit in square feet (ft2). So if you have a 5 inch hose how do they get A=0.136 ft2 ? And I know the velocity already v= velocity in ft per second.
Stephen La Rocque lui répond.

How do I convert mcg to ml? 2008-01-27

David pose la question :
How do I convert mcg to ml?
Stephen La Rocque lui répond.

O.T.T.F.F.S.S 2008-01-25

Omar pose la question :
What is the next letter in the following sequence:

O.T.T.F.F.S.S
Penny Nom lui répond.

Three consecutive odd integers 2008-01-24

daniel pose la question :
find three consecutive odd integers such that three times the second minus the third is 11 more than the first. help! i have x+1, x+3, x+5 as my 3 odd integers is this correct its been a while.
Penny Nom lui répond.

1/2, 1/2, 3/8, 1/4, 5/32, 3/32, 7/128 2008-01-22

Neil pose la question :
Find the next two terms in the following number sequence

1/2, 1/2, 3/8, 1/4, 5/32, 3/32, 7/128

Find a general rule for the nth term of the sequence
Penny Nom lui répond.

Choosing 6 numbers from 42 2008-01-19

Marcus pose la question :
If i have 42 numbers to choose from and i could only choose 6 numbers at a time without choosing the same number twice in the same row, how many possibilities are there?
Penny Nom lui répond.

A sector of a circle 2008-01-17

Amandsa pose la question :
What is the formula for finding the sector of a circle?
Penny Nom lui répond.

A large concrete shape 2008-01-16

Keith pose la question :
what is the cubic yards of an area that is not a perfect 1/4 circle? The dimensions are 100ft. x 60ft. x 125ft. curcumferal arch x 3ft. depth?
Stephen La Rocque lui répond.

The area of a sector of a circle 2008-01-11

Serenity pose la question :
A denotes the area of a sector of a circle of radius r formed by the central angle theta. Find the area A if r=10 meters and theta = 1/2 radians.
Penny Nom lui répond.

Multiplying numbers in bases other than 10 2008-01-08

Imaiya pose la question :
In class we've been learning about numbers with a base other than ten. For example, base 7, base 5, and base 6. What's really stumping me is how to multiply these numbers, when they aren't a base of 10. I've had it explained to me once, but don't seem to understand it. Here are the equations, and I've listed the first few numbers for that particular base.

Base 5: 0,1,2,3,4,10,11,12,13,14,20 etc... The Equation: 34 x 42 Base 9: 1,2,3,4,5,6,7,8,10,11,12,13,14, etc... The Equation: 56 x 78

If you could explain to me how to multiply numbers with any type of base, I'd really appreaciate it. Also if you could show me how to do one of the questions that I listed, that would really help me =) Thanks so much, and once again, thank you for your great site!
Stephen La Rocque lui répond.

Practical applications of sequences 2008-01-01

carl pose la question :
can you give me examples of different kinds of practical applications of sequences?
Penny Nom lui répond.

Find the lengths, and explain in a 'let statement' 2007-12-20

Cordilla pose la question :
the length of the sides of a triangle are 3 consecutive whole numbers. The perimeter of the triangle is 102 meters. Find the lengths, and explain in a' let statement'.
Stephen La Rocque and Harley Weston lui répond.

A 45-45-90 triangle 2007-12-13

Aaditya pose la question :
explain to me please how to do the 45-45-90 theorem when one of the legs(not the hypotenuse) is 3. How do you find the remaining two sides? please help me out.
Leeanne Boehm lui répond.

How many houses must they paint? 2007-12-12

Natalie pose la question :
The question is: Four boys work together,painting houses for the summer.For each house they paint they get 256 pounds. If they work for four months of the summer and their expenses are 152 pounds per a month, how many houses must they paint for each of them to have one thousand pounds at the end of the summer?
Penny Nom lui répond.

Imprecise measurements 2007-12-09

Sara pose la question :
Hi! A water tank, in the shape of a cuboid (length 1.6 m, height 1.2 m, breadth 0.8 m), is full of water. Water is drained from the tank at a rate of 8 litres per minute. The dimensions of the tank are given to the nearest 10 cm. The rate at which the water is drained from the tank is given to the nearest 0.5 litres per minute. (a) Calculate the smallest possible time to drain the tank. (b) Calculate the greatest possible time to drain the tank. Many thanks!!!
Stephen La Rocque lui répond.

Three consecutive numbers 2007-12-08

Aris pose la question :
The product of 3 consecutive numbers is 1716. Find their sum.
Stephen La Rocque lui répond.

A portion of a circle 2007-12-07

Richard pose la question :
please could you tell me the formula and answer to the following. I have a circle portion with a radius of 150mm and an angle of 120 deg. If an arc is drawn from one point to the other as the radii touch the circle circumference, i need to know the area of the segment and the formula to carry out the answer. Many Thanks
Penny Nom lui répond.

A right triangle 2007-12-06

Shubhomoy pose la question :
The co-ordinates of a hypotenuse are (1,3) and (-4,1). Find the equations of the perpendicular sides.
Harley Weston lui répond.

Representing different bases 2007-12-05

Sudhir pose la question :
What does a number subscripted to another one denote? (I know that a number superscripted to another denotes the power, but the subscript number is something I have never seen before.)
Stephen La Rocque lui répond.

Percentage increase in profit 2007-12-04

Dee pose la question :
If I had a certain % increase in profits for the entire year, why can't I add the profits I made for the first 1/2 of the year to the profit I made in the second 1/2 of the year to get the total year end profit percentage? Or how can I compare the increase/decrease for each 1/2 of the year to the total % increase/decrease?
Penny Nom lui répond.

Proving a quadrilateral is a rhombus 2007-12-03

Jeanie pose la question :
How do you prove that a quadrilateral is a rhombus because the diagonals of the quadrilateral are perpendicular and bisect each other using the 2-column proof method?
Stephen La Rocque lui répond.

O,T,T,F,F,S,S,?,?,? 2007-11-28

Kim pose la question :
What are the next 3 letters in this sequence?

O,T,T,F,F,S,S,?,?,?
Stephen La Rocque lui répond.

Direct and inverse variations 2007-11-27

Julie pose la question :
Please Help I do not understand this question. X varies directly as the square of S and inversely as T. How does X change when S is doubled ? When both S and T are doubled ? I appreciate your help with this problem.
Stephen La Rocque lui répond.

Elimination of mayan prisoners 2007-11-19

Jim pose la question :
An evil Mayan emperor decides to make an example of 1,000 prisoners. He stands them in a circle with numbers one to a thousand marked on their shirts. He then starts counting: "one in, two, in three out" The third man is immediately executed. This continues round and round and round the circle. While the number in the circle shrinks, every third prisoner is pushed out and executed. And it continues even when there are only two prisoners left alive. What number is on the last prisoner's shirt?
Victoria West lui répond.

Sides and vertices 2007-11-17

derek pose la question :
What is the correct name for a 2D geometric shape that would look like one slice from a round pizza and how may sides and vertices would it have? I believe you would say it has one vertex and two sides with the curved boundary not resulting in vertices or a side. Your help is much appreciated.
Chris Fisher and Walter Whitelty lui répond.

A matrix equation 2007-11-16

stephanie pose la question :
Im supposed to solve
( 1 tan =E8/2) ( 1 tan =E8/2)^(-1)
(-tan =E8/2 1 ) (-tan =E8/2 1 )

Matrix AA<(-1)=I
Penny Nom lui répond.

Two sequences 2007-11-14

Kim pose la question :
Pattern........what comes next?

1,4,9,16,25,_____,____
1,4,9,16,27,40,__________,_______
Penny Nom and Gabe Potter lui répond.

Radial motion 2007-11-13

abdulai pose la question :
a circular saw with diameter 18.4cm rotates at 2400rpm. What is the angular speed of a point on the edge of the saw blade in radians per second?
Penny Nom lui répond.

What number best completes the series? 2007-11-12

Grace pose la question :
What number best completes the series?

2 3 7 13 27 ____
Stephen La Rocque, Penny Nom and Harley Weston lui répond.

The sequence 3,12,26,45.... 2007-11-12

Tra pose la question :
I can seem to find the realtionship in these sequence of numbers, I am looking for the next three. How can I determine that, I have tried everything??!!!

3,12,26,45....
Penny Nom lui répond.

Meters per second to miles per hour 2007-11-08

Niecey pose la question :
If Greg was timed at 0.91 seconds for 10 meters running the 100 meter dash, at that speed, could he pass a car traveling 15 miles per hour in a school zone?
Penny Nom lui répond.

The base and height of a triangle triangle 2007-10-31

mike pose la question :
How do you find the length of the base or the height of a triangle if the area is 30 square feet?
Penny Nom lui répond.

Subsets of a set 2007-10-30

Snehal pose la question :
1. Let an denote the number of subsets of f{1,2, 3.... n}including the empty set and the set itself.)
a) Show an = 2an-1
b) Guess a formula for the value of an and use induction to prove you are right
Stephen La Rocque lui répond.

Dividing a segment into 3 congruent parts 2007-10-30

Carolyn pose la question :
I am doing construction. I have a line segment drawn. I need to divide a segment into 3 congruent part. How do I do that?
Penny Nom lui répond.

Variation 2007-10-29

deeqa pose la question :
1. A car traveled 175mi at a certain speed. If the speed had been 20mph faster, the trip could have been made in 1hr less time. Find the speed

2. The average weekly allowance A of children varies directly as their grade level, G. If the average allowance of an 8th-grade student is $8.56 per week, what is the average weekly allowance of a 5th-grade

The time T required to do a job varies inversely as the number of people P working. It takes 2hr for 4 working. It takes 2 hrs for 4 volunteers to distribute flyers to a neighborhood. How long would it take 12 volunteers to complete the job?
Penny Nom lui répond.

Combinations and horse races 2007-10-28

Ian pose la question :
How do I calculate the number of combinations for: Horse races,1 horse in each race.I want all combinations covered. e.g.5 races, 1 horse in each race. R 1&2, R 1&3,R 1&4, R 2,3,4,5, R 1,2,3,4,5 etc etc.I have worked it out manually to 27 combinations but if I want to cover more than 5 it will be a big excercise to work out the cost manually. Many Thanks
Victoria West lui répond.

Is there a practical use for radian measure? 2007-10-26

Paula pose la question :
Is there a practical use for radian measure in any profession? Which professions might us radian as opposed to degree measure?
Harley Weston lui répond.

The perimeter of a circle sector 2007-10-25

sara pose la question :
Hi! The area of a sector of a circle is 25 sqcm. The radius of the sector is 6 cm. Calculate the perimeter of the sector. Many thanks!!!
Penny Nom lui répond.

A sixfold increase 2007-10-24

Fred pose la question :
If I have $500 and it grew to $3,000, what is the correct description of the increase? Is it a sixfold increase (sextupled), or a fivefold increase (quintupled)? When I divide $3,000 by $500, the result is six, therefore, a sixfold increase?
Stephen La Rocque lui répond.

Converting bases 2007-10-24

Johanna pose la question :
Is there an easy way to convert from base to base. For example, base 5 to base 9 or base 2 to base 4 etc
Stephen La Rocque and Penny Nom lui répond.

The nth term 2007-10-18

shannon pose la question :
Ok , what i am having problems with is the nth term. I get how the numbers come together, but i am having trouble with finding the nth term.
Penny Nom lui répond.

Paying with silver - Part 2 2007-10-17

Shanna pose la question :
The paying with silver problem. I understand how to do the problem, but could you please explain how you would use base 2 arithmetic to solve it.
Penny Nom lui répond.

the sum of two consecutive integers is 51 2007-10-17

Keira pose la question :
the sum of two consecutive integers is 51
Penny Nom lui répond.

0,1,2,3,6,11,20,37,68... 2007-10-16

Pat pose la question :
Describe the rule for this pattern: 0,1,2,3,6,11,20,37,68... Thanks
Penny Nom lui répond.

How much water is in a hose? 2007-10-12

Bryan pose la question :
I need to know how much water (gal) is in a hose thats 100' long by 5" in dia. Thanks
Stephen La Rocque lui répond.

77,49,36,18,... 2007-10-11

Kim pose la question :
Find a pattern and predict what comes next in this sequence 77,49,36,18,________________.
Penny Nom lui répond.

Inverses of Quadratic Functions 2007-10-11

Elliot pose la question :
I'm a special education tchr trying to demonstrate how to find the inverse (using algebra) of quadratic functions. Any help would be greatly appreciated.
Steve La Rocque and Harley Weston lui répond.

Base 10 to base 5 2007-10-09

Angela pose la question :
I've been searching online for the past week and I cannot find an Algorithm to convert from base 10 to base 5. Can anyone give me a step-by-step instruction on how to do this?
Stephen La Rocque lui répond.

Equation of a circle circumscribing a triangle with given vertices 2007-10-01

Randy pose la question :
How do I determine the equation of a circle when it is circumscribed by a triangle whose vertices are (-1, 6), (3, -2), and (2, 5)?
Stephen La Rocque lui répond.

A sequence of numbers 2007-09-30

eleanor pose la question :
can you find the nth term of the sequence ( n starts at three)

1=?
2=?
3= 4
4= 10
5=20
6 = 35
7= 56

i only hand the 3rd 4th 5th 6th and 7th numbers in the sequence

can you please tell me how to find the nth term and what is it :)
Stephen La Rocque and Victoria West lui répond.

The nth term 2007-09-29

zoe pose la question :
what is the nth term for the following sequence...
5, 2, -1, -4
Leeanne Boehm lui répond.

Describe the pattern 2007-09-29

Baffled pose la question :
Given a rule, extend a pattern and describe it in informal mathematical language:

a) 1, 6, 16, 36, _

b) 2, 6, 14, 30, _

c) 1, 8, 22, 50, _

d) 3, 9, 27, _

e) 2, 7, 17, 37, _
Stephen La Rocque and Penny Nom lui répond.

Four consecutive integers 2007-09-28

Joshua pose la question :
We were given a question that involved consecutive integers. I can not seem to solve this question and I am the top student in my class.The question states: Find four consecutive integers such that twice the sum of the two greater integers exceeds three times the first by 91. How do you solve this question? Thank you very much for your support.
Penny Nom, Stephen la Rocque and Claude Tardif lui répond.

A sector of a circle 2007-09-26

A student pose la question :
hi im stuck on this question. i have tried to do some, could you please che= ck it and help me.the answers i have worked out are in red. the question is= attached. thank you.
Penny Nom lui répond.

The nth term 2007-09-25

Bobby pose la question :
whats the nth term of 2,12,22,32 ?
Penny Nom lui répond.

A geodesic dome 2007-09-25

Roger pose la question :
In my Science-Fiction series, I have a Dyson's Sphere tiled with regular hexagons. The number of hexagons is over 300,000 and the radius of the Sphere is roughly 80,000,000 miles. The actual size of the Sphere and hexagons have been left flexible until I can come up with a definite number of hexagons that would fit. My problem is the pattern of hexagons which would fit within the sphere without leaving gaps or overlapping.

My best guess has been to use four equilateral triangles composed of 78606 hexagons, (396 per edge) arranged around the sphere with six 'zippers' to connect them and four 'caps' at the points, for a total of 316804 hexagons. Given the fact that each Hex is the same size, does this seem plausible? Is there some pattern formula I can use to play with these figures? Simple divsion of areas will not work if the number derived will not fit into the pattern to leave a perfectly tiled surface. Thank you.
Chris Fisher lui répond.

The sequence 2,4,7,11,16,22 2007-09-22

Simon pose la question :
I thought i understood how to explain how to work out the nth term on a sequence of numbers until my son had this sequence to work out - 2,4,7,11,16,22
We have worked out the 2nd differance is +1 but nothing else seems to fit. Im sure the answer is staring us in the face but cant see the wood for the trees!
Denis Hanson and Steve La Rocque lui répond.

Finding equations, intersection point of two lines at right angles 2007-09-22

Yaz pose la question :
Find the equation of the line joining A(-1,-9) to B(6,120). Another line passes through C(7,-5) and meets AB at rigth angle of D. Find the euation of CD and calculate the co-ordinates of D.
Stephen La Rocque lui répond.

A fraction sequence 2007-09-21

marissa pose la question :
i have read the examples you have on fraction sequences, but i am still having a hard time understanding how to figure this out. for example:

__ 1 2/5 __ 3 __ __ __ __7
Stephen La Rocque lui répond.

Letter number sequence 2007-09-21

Hope pose la question :
The challenge problem of the week in 6th grade math is a letter number sequence. J 1 F 8 M 1 A 0 M 1 J 0 J 1 _ _ _ _ _ _ _ _ _ _ They are to find the next 10 letters and numbers in the line. They were given a hint : look at the letter sequence by themselves and you should recognize it. Does it just repeat starting with the F 8 M 1 etc.? Thank you for your help.
Claude Tardif lui répond.

The hypotenuse 2007-09-20

Kasey pose la question :
What is the hypotenuse of 96 squared and 108 squared?
Penny Nom lui répond.

What is the inverse function of y=x^3 +x? 2007-09-19

saman pose la question :
what is the inverse function of y=x^3 +x
Harley Weston lui répond.

Number sentences 2007-09-15

jen pose la question :
list the addition number sentences that can be written using two sets of cards with the numbers 5 6 and 7. which number sentences have the same addends but show a different order?,,,,,,,,,,,,,,Ithis is for my son in 3rd grade and for the life of us we can't figure it out,,thanks for this elementary help
Harley Weston lui répond.

The nth term 2007-09-13

Rookin pose la question :
Can you help me find the nth term for this ... 20,17,14,11,8 i'm really confused oh and could you also tell me how you got the answer?
Steve La Rocque, Claude Tardif and Harley Weston lui répond.

The perimeter of a semi-circle 2007-09-11

Confused pose la question :
What is the formula for the perimeter of a semi-circle? Can you please help me out!!! I need this answer by tomorrow.
Stephen la Rocque lui répond.

What are the next two terms? 2007-09-11

Sassy pose la question :
I can't figure out what the next two integers in this pattern are 3,9,6,12,9 are.
Stephen la Rocque lui répond.

A sequence of fractions 2007-09-10

mitch pose la question :
find an expression for T(n), the nth term of the sequence
1/5, 3/8, 5/13, 7/20, 9/29
Stephen La Rocque lui répond.

Segments on a line 2007-09-10

Cathy pose la question :
This question was on my daughter's geometry assignment. Write a general rule of formula for finding the number of segments that can be named by a given number of points on a line. For example, 2 points on a line = 1 line segment; 3 points on a line = 3 segments; 5 points on a line = 10 segments.
Penny Nom lui répond.

The nth term 2007-09-09

Conor pose la question :
Please can you help me with this question on the subject of the Nth term. 3.5, 5, 6.5, 8, 9.5

5.1, 7.2, 9.3, 11.4...
Penny Nom lui répond.

nth term in this series 2007-09-07

danii pose la question :
im trying to solve the nth term for this pattern.

1 3 6 10 15 21 28

any help would be appretiated
Stephen la Rocque lui répond.

The next term 2007-09-07

Ariel pose la question :
Please explain to me why -3^2 is a -9. One calculator give me an answer of positive 9.

WHAT IS THE NEXT TERM IN Each sequence/ What is its term number?

1/2, 2/3, 3/4, 5/6 6/7

1, 1/4, 1/9, 1/16
Stephen la Rocque lui répond.

A sequence 2007-09-06

aimee pose la question :
i have the sequence 1,5,14,30,55 and i have been told to use An squared times Bn times C and my working should look like this
1 5 14 30 55
      4 9 16 25
         5 7 9
            2 2

But how do i do this
Penny Nom lui répond.

A sequence of fractions 2007-09-05

Arjun pose la question :
1/2 3/5 5/8 7/11- need to find the nth term.

I did search the data base & found one for fractions but what I want to know is when calculating nth term for the denominator in the example give in your database how do we get (n-1)? When we deduct the actual term with the one that is in the table give in your example it is more that one. Could you please explain solving the above example?
Penny Nom lui répond.

The first five terms 2007-09-04

JP pose la question :
Find the first five terms of a sequence with the nth term n^2+2n+1 and 2^n.
Penny Nom lui répond.

Speed of sunrise 2007-09-04

Robert pose la question :
Facing west in a car, you are watching the sun rise (through the rear view mirror). It peaks the horizon, you take off driving. How fast would you have to drive, to see it rise again?
Stephen La Rocque lui répond.

2,6,7,21,22,66,67 2007-08-28

EDWIN pose la question :
this doesnt make any sense to me....... i cant find the pattern...

2,6,7,21,22,66,67
Leeanne Boehm and Stephen La Rocque lui répond.

Applications of sequences and series 2007-08-27

Trish pose la question :
I'm a grade 12 learner working on a math project based on sequences and series. I'd like to know the different types of sequences and series such as fibonacci, fourier, farey, etc.

I've already used the Fibonacci Sequence and Harmonic Series and need two more. The simpler the sequence or series type the better.

I'd also like to know in which non-mathematical areas use sequences and series and how. Areas such as engineering or science.
Penny Nom lui répond.

Where do you use trigonometry? 2007-08-21

jenny pose la question :
where do you use trigonometry besides architecture and engineering?
Stephen La Rocque lui répond.

The tens digit 2007-08-21

Arul pose la question :
Hi.. Please help me on this question.. Sequence 2, 7, 22,…after the first three terms, each term is three times the previous term plus 1, a(n+1)=3an + 1. What is the sum of tens digit 33rd and tens digit of the 35 term?
Penny Nom lui répond.

Common factors 2007-08-19

John pose la question :
I have problem factorising 2p^3 - 34p. Please advise me.
Leeanne Boehm, Steve La Rocque and Penny Nom lui répond.

Percentage change 2007-08-19

nona pose la question :
If inputs increase by 30% and outputs increase by 15%, what is the percentage change in productivity?
Stephen La Rocque lui répond.

Area and perimeter 2007-08-16

sheryl pose la question :
a 50*70 horse pen is 240 feet and 3500 square feet a 60*60 horse pen is 240 feet and 3600 square feet why is there a 100 square feet difference?
Penny Nom lui répond.

Percentage change 2007-08-13

Karen pose la question :
I need a formula for calculating percentages in Excel. For example, we = sold 4 units of an item one month, and 105 units the next. I need a = formula to calculate the percentage increase in sales units. Also, if = 5251 were sold one month and 651 the next, what is the formula for = calculating the percentage difference? Please help, thank you.
Penny Nom lui répond.

Twenty dining tables 2007-08-13

priya pose la question :
Utkarsh bought 20 dining tables for Rs 120000 and sold these at a profit equal to the S.P of 4 dining tables.Find the S.P of one dining table.(give the answer in statements)
Stephen La Rocque lui répond.

A right triangle 2007-08-11

Peter pose la question :
Ok, is it possible to find the height and base of a right triangle when all the information you are given is the length of the hypotenuse?
I also know that the angle between side b and the hypotenuse is 45 degrees. please help.
Walter Whiteley lui répond.

4,18,48,100, __ 2007-08-07

Jeremy pose la question :
What is the next number in the following sequence?
4,18,48,100, __
Leeanne Boehm and Stephen La Rocque lui répond.

Linear systems and inverses 2007-08-06

Marsia pose la question :
explain how inverses are used to solve linear systems.
Penny Nom lui répond.

Angular speed 2007-08-05

Virginia pose la question :
the engine of a sports car rotates at 5,000 revolutions per minute (rpm). calculate the angular speed of the engine in radians per second. use 2n radians = 1 revolution
Stephen La Rocque lui répond.

A sequence of numbers 2007-07-27

Shamik pose la question :
Question: A sequence of numbers is defined in the following way.
B(1) = 1
B(n) = B(n-1) + {Sum of the digits of B(n-1)} for n > 1.

B(1) = 1
B(2) = 2
B(3) = 4
B(4) = 8
B(5) = 16
B(6) = 23
B(7) = 28
B(8) = 38
B(9) = 49
::::::::: and so on ...

Is the number 123456789 a term in the given sequence?

Shamik
Claude Tardif lui répond.

Countable and uncountable sets 2007-07-24

Mac pose la question :
Hi, i tried to read few webpages related to the countably infinite and uncountable sets. Even i read few questions from this forum.

But i am not convinced with this explanation. If you have any good book that explains this in layman term, please redirect me to that.
1) Can you please explain what is the difference between these too ?
2) How could you say set of Natural number and set of even numbers are countably infinite ?
N={1,2,3,...} and Even= {2,4,6,...}
When an element in the even set is some 2n, we will map it to 'n'.So now we have a bigger number(2n) right ?
Sorry, i didn't understand that.
...

Can you please help me out to understand that ?
Harley Weston lui répond.

Equality of sets 2007-07-23

Mac pose la question :
Hi, I learnt set theory recently. My teacher and few of the weblink actually give different definition for basic set. Can you please solve this ?

My teacher says, {1,2,3} and {1,1,2,3} is also set.
But in this link http://library.thinkquest.org/C0126820/setsubset.html it says,
"A set has no duplicate elements. An element is either a member of a set or not. It cannot be in the set twice."
and "{1, 2, 3} is the same as the set {1, 3, 2, 3, 1}"

My question is,
1. Whether duplicates allowed in the set or not ?
2. Even if the duplicates are allowed, {1,2,3} and {1,1,2,2,3,3} are same or not ?
Penny Nom and Harley Weston lui répond.

Comparing flow rates of two pipes 2007-07-14

Kenneth pose la question :
If two water pipes are 3 feet long, but one of them has a 1 foot diameter and the second has a 1 1/2 foot diameter, what simple mathematical method can be used to determine how much faster one pipe can drain water than the other pipe?
Stephen La Rocque lui répond.

Can't find circumference of an ellipse 2007-07-06

Michele pose la question :
I need to figure the circumference of an oval and I know the height and width.
Penny Nom lui répond.

Log base 2 of log base 2 of x 2007-06-27

alex pose la question :
y = log base 2 of lag base 2 of x The slope of the tangent to the given curve at its x-intercept is..?
Harley Weston lui répond.

The area of part of a circle 2007-06-21

Sarah pose la question :
Hi, I need help finding the area of a part of a circle that involves a chord. I need this answer/help very soon if at all possible. I have attached a drawing of what I am trying to solve. Thank you for your help! Sarah!
Penny Nom lui répond.

Finding the center of an ellipse 2007-06-20

Sima pose la question :
find the center of the ellipse with the equation 3x^2 +4y^2+18x-32y-5=0
Penny Nom lui répond.

What is the 100th term? 2007-06-15

George pose la question :
I have the sequence 50,120,235,406,644

the 1st difference is 70,115,171,238
the 2nd difference is 45,56,67
the 3rd difference is 11,11

i used the a*n^3+b*n^2+c*n+d rule but the a turns out to be a decimal because 11/6 is 1.833333333 and so i cant find the formula for the 100th term term.
Penny Nom lui répond.

Percentage increase and decrease 2007-06-13

Anna pose la question :
I just want to if the following formula is used for the computation of a PERCENTAGE DECREASE:

Old Value - New Value/ Old Value x 100%

My immediate superior is under the impression that the said formula works ONLY for the computation of a percentage INCREASE. He believes that the formula for a percentage DECREASE:

Old Value - New Value/ NEW Value x 100%

On this score, I want to know the correct formula for the computation of percentage decrease. Thank you so much.

Penny Nom lui répond.

Composition functions 2007-06-12

Gilligan pose la question :
Find functions f and g so that f(g(x)) = H.
(1) H(x) = (1 + x^2)^(3/2)
(2) H(x) = int(x^2 + 1)
I don't know where to start.
Stephen La Rocque lui répond.

A sequence of circles 2007-06-11

Ann pose la question :
Please help with solving the following problem!!! A circle is inscribed in an equilateral triangle with a side of length 2. Three circles are drawn externally tangent to this circle and internally tangent to 2 sides of the triangle. 3 more circles are drawn externally tantgent to these circles and internally tangent to 2 sides of the triangle. if this process continued forever, what would be the sum of the areas of all the circle? the answer 1 parent came up with was Pie over 2, but we don't know how he did it. Can you please show the work or explain the answer to this problem? Thank you Ann p s my daughter is in 9th grade math.
Steve La Rocque, Chris Fisher and Penny Nom lui répond.

How many terms in this sequence? 2007-06-11

Jesse pose la question :
How do I find how many terms are in the sequence? 51, 48, 45, ...., -75
Stephen La Rocque and Penny Nom lui répond.

The intersection of two planes 2007-05-31

Sarim pose la question :
How to find a intersection of two planes?
Penny Nom lui répond.

Water tank volume 2007-05-29

Cecelia pose la question :
I HAVE A SEMI CIRCULAR TANK AGAINST A WALL MEASURING 6'10" ACROSS THE WIDEST PART AND 3' FROM THE WALL TO THE FRONT OF THE TANK. THE DEPTH IS 14". PLEASE HELP ME TO CALCULATE THE VOLUME OF WATER IN THE TANK.
Stephen La Rocque lui répond.

A point on a semicircle 2007-05-28

arun pose la question :
a semi circle is drawn with ab as diameter from p a point on ab a line perpendicular to ab is drawn meeting circumference of semi circle at c, ac = 2cm, cd = 6cm find area of the semi circle?
Penny Nom lui répond.

The surface area of a fire hose 2007-05-26

Vanessa pose la question :
Why do we need to find the surface area of a fire hose (cylinder).
Stephen La Rocque lui répond.

The circumference of an ellipse 2007-05-25

Graham pose la question :
I have an ellipse that I need to find the circumference of. It is 40ft at its longest point and 25ft at its shortest
Penny Nom lui répond.

Normal distribution 2007-05-24

Paula pose la question :
Consider a data set that is normally distributed. The mean of the data set is equal to 10,000.
a.) Suppose that, for this data set, 10,625 has a "z-value" = 2.5. Solve for the standard deviation of the data set.
b.) Solve for the "z-value" of 9,900.
Penny Nom lui répond.

Base seven 2007-05-19

Dan pose la question :
A number X is converted to base 7 and becomes a four digit number. Its leftmost digit is removed and written again as the rightmost digit. The number thus obtained is twice X. Find the decimal representations of all such numbers X.
Penny Nom lui répond.

Parabolas in the real world 2007-05-18

Katherine pose la question :
Hi, my name is Katherine, and my mean old math teacher just assigned us a test in which we have to write two examples of how parabolas are used in the real world, each one page single spaced, size 12!! I know you have already answered some questions like this, but I still don't understand the whole baseball thing, and any other way parabolas are used. And how I can write a whole page on it. But that's my problem, not yours, I just need help with a little explanation on how parabolas are actually used today. I know this might be kind of confusing for you, but imagine how it is for me!!
Stephen La Rocque lui répond.

Comparing the areas of various shapes 2007-05-16

Kathy pose la question :
If the perimeters are the same, which has the greater area, a circle, a square, an ellipse, or an octagon?
Stephen La Rocque lui répond.

Maximizing the volume of a cone given the slant length 2007-05-14

Christina pose la question :
A coffee filter for a new coffee maker is to be designed using a conical filter. The filter is to be made from a circle of radius 10cm with a sector cut from it such that the volume of coffee held in the filter is maximised. Determine the dimensions of the filter such that the volume is maximised.
Stephen La Rocque and Kerstin Voigt lui répond.

Finding the hypotenuse without Pythagorus 2007-05-11

Shelbie pose la question :
How do i find the hypotenuse of a right traingle not using the pythagorean thereom if i have the measurements of the legs?
Stephen La Rocque lui répond.

Probability of H.I.V. tests 2007-05-07

Danielle pose la question :
A medical test detects H.I.V. Among those who have H.I.V., the test will detect the disease with probability 0.95; among those who do NOT have H.I.V., the test will falsely claim that H.I.V. is present with probability 0.0125. Among those who take this test, 4% have H.I.V. The test is given to Lucille, and indicates that she has H.I.V. What is the probability that Lucille actually has H.I.V.?
Stephen La Rocque lui répond.

A point inside a circle 2007-05-04

edgemitter pose la question :
There is a point inside a circle (but not in its center) where two perpendicular secants intersect, dividing the circle into four regions with different area. Calculate the area of the four regions
Walter Whiteley lui répond.

Hypotenuse 2007-05-03

ashley pose la question :
how do you find the hypotenuse
Penny Nom lui répond.

3, 6, 12, 21, 33, 48, 66 2007-05-02

Siew pose la question :
I need to find the nth term formula for the sequence :

3, 6, 12, 21, 33, 48, 66
Stephen La Rocque lui répond.

Percentage change 2007-05-01

katie pose la question :
i no many people have asked about this but im still unsure what is percentage change i have my ks3 tomoro so please reply asap thankz
Penny Nom lui répond.

The sum of two or more consecutive integers 2007-04-26

nana pose la question :
some numbers can be written as the sum of two or more consecutive integers(we consider positive integers only) other number (eg. 4) cannot be express in this way.
let us call a number which can be expressed in this way a SOALTCI( sum of at least two consecutive integers)
a). list the first few SOALTCI and conjecture the general formula.
b). Prove that any number of the given form(in your answer (a)) is a SOALTCI
Penny Nom lui répond.

A triangle problem 2007-04-23

Dimitri pose la question :
In the triangle ABC, M is the midpoint of AB and N is the midpoint of AC. Prove that CM and BN cannot bisect. (I can prove it by contradiction if it is a scalene triangle, but i cant seem to prove it for isosceles)
Chris Fisher lui répond.

Two lines intersect at a right angle 2007-04-20

ellen pose la question :
The line with the equation 3x + by = 6 intersects with the line 6y + ax = c at right angles at the point (4,6). Determine the values of a, b & c.
Stephen La Rocque lui répond.

The second derivative 2007-04-14

Gerry pose la question :
In mathematical context,what do you understand by the term "Second Derivative"
Penny Nom lui répond.

Intersection of a line and a circle 2007-04-12

gaby pose la question :
The sum of two numbers is 9. The sum of the squares of the two numbers is 41. Find the numbers.
Steve La Rocque and Melanie Tyrer lui répond.

Choosing 6 from a set of 12 2007-04-12

Darren pose la question :
there are 12 numbers (1-2-3-4-5-6-7-8-9-10-11-12) how many times can i pick 6 different numbers?
Stephen La Rocque lui répond.

Where will volume 13 go? 2007-04-12

Shawn pose la question :
A novice librarian shelved a twelve-volume set of encyclopedias in the following order from left to right. Volumes 8, 11, 5, 4, 9, 1, 7, 6, 10, 3, 12, and 2. Using her system, where will volume 13 go?
Stephen La Rocque and Penny Nom lui répond.

Pythagoras was right 2007-04-11

Vineet pose la question :
in a right angle triangle, hypotenuse side is less than the sum of other two sides, how the square of hypotenuse is equal to the sum of squares of other two sides?
Stephen La Rocque lui répond.

What are the first 3 terms of this sequence 2007-04-10

kyrie pose la question :
what are the first 3 terms of this sequence n-2 divided by n squared
Stephen La Rocque lui répond.

4,7,16,43,... 2007-04-04

claire pose la question :
What is the explicit definition for the sequence 4,7,16,43,...?
Stephen La Rocque and Penny Nom lui répond.

What is the hypotenuse of a right traingle 2007-04-04

debbie pose la question :
what is the hypotenuse of a right triangle with sides of 38 meters and 24.2 meters.
Stephen La Rocque lui répond.

A set of points in space 2007-04-04

Lenny pose la question :
What is a set of points in space the same given distance from its center point called?
Stephen La Rocque lui répond.

Algebra 2007-04-03

Emily pose la question :
9,365 and 2,242 added to the difference between 255 and half of a number is 11,784. What is the number?
Haley Ess lui répond.

In what base does 25+25=51? 2007-04-03

Jenna pose la question :
In what base does 25+25=51?
Stephen La Rocque and Penny Nom lui répond.

A geometric series 2007-04-03

jessica pose la question :
If a geometric series includes 54-18+6-2 as its fifteenth through eighteenth terms, find the sum of the second through the fifth term, inclusive.
Stephen La Rocque lui répond.

Direct and inverse Variation 2007-04-03

liz pose la question :
how do you tell if an equation varies Directly or Inversely? ex.

x= 2y or

xy+12=3

i know that if you have three numbers (x. y, z) that it varies jointly but how do you tell if it is Inverse or Direct?

Thanks for the Help!

-liz
Stephen La Rocque lui répond.

What does inverse graph represent? 2007-03-30

san pose la question :
what does inverse graph represent?
Penny Nom lui répond.

Is the inverse of a function always a function? 2007-03-29

San pose la question :
Is the inverse of a function always a function? Please justify. Thank You!
Penny Nom lui répond.

A beam on a lighthouse 2007-03-28

Lisa pose la question :
A beam on a lighthouse 2000 metres away from the nearest point P on a straight shoreline revolves at the rate of 10 pi radians per minute. How fast is the beam of the light moving along the shoreline when it is 500 metres from P?
Stephen La Rocque lui répond.

The angles in a right triangle 2007-03-28

Golaan pose la question :
I need the to understand the formula for finding either of the acute angles of a right triangle given it's hieght length and base length. I want to find the degrees of either accute angle. So for this example I have a right triangle with a height of 410 meters and a base length of 1,700 meters. I don't understand cosine, sine, and tangent or the other ones at all. So if the solution includes those (which I believe it does) could b very verbose yet in a very elementary way?

The purpose of ths is that I have to define the general incline angles (or grade) of various areas of terrain. I know the distance by map and also the the altitude at either endpoint.
Penny Nom lui répond.

The foci of an ellipse 2007-03-27

Brad pose la question :
I am trying to figure out how to find the foci of an ellipse x^2/7 + y^2/16 = 1. Since 16 is the largest denominator I know the major axis is going to be the y axis. Do I now take 7-c^2=16. c^2=16-7, c^2=9, c=3. So is my foci (0,+-3).
Penny Nom lui répond.

An inheritance problem 2007-03-23

Carl pose la question :
A father of 3 boys, who owns 17 horses dies. He leaves his first son 1/2 of the horses. The sons hate each other. The father leaves the second son 1/3 of the horses. They are ready to kill each other. He leaves his youngest son 1/6 of the horses. Without cutting the horses into pieces how do they split the horses? I heard this puzzle when I was 12 years old. 1968 The preacher rides up on his horse and said "If I give you my horse will you quit fighting ? They agree to stop fighting?" Why?
Penny Nom lui répond.

Two consecutive odd numbers 2007-03-19

Alicia pose la question :
The sum of two consecutive odd numbers is divisible by 4.

Can you make similar statements about the sum of three consecutive odd numbers and of four consecutive odd numbers? Generalize your findings.

I tried :
n= smallest odd number therefore the next = n, n+2 and the second =n+4 and the third = n+6 Now n+ n+2+n+4+n+6/4
Please help I am not sure of this I am just trying
Penny Nom lui répond.

Choosing numbers with no two consecutive 2007-03-15

Meghan pose la question :
How many combinations are there of 3 numbers chosen from 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 but where no 2 of the 3 numbers are consecutive?

Thank you! -Meghan
Penny Nom lui répond.

A truncated cone 2007-03-10

Russell pose la question :
Hello, I have attempted to use two of your answers already given and had no real success. This young lady is making a cat food dispenser using a truncated cone. The top of the cone as a diameter of 5 inches with a height of 6 1/2 inches and diameter of 3 inches for the bottom.

Could you please map out a solution for the both of us to understand? Thank you so much for your time and for this wonderful service.

Russell
Penny Nom lui répond.

Seven digit account numbers 2007-03-09

Miranda pose la question :
Account numbers for the Central Oil Company consist of seven digits. If the first digit cannot be 0, how many account numbers are possible? Thank you so much!!!
Penny Nom lui répond.

A circle is stretched horizontally by a factor of 2 2007-03-07

bob pose la question :
I was wondering if you could double check my work?

the question is as follows:
The circle X^2+y^2-2x-3= 0 is stretched horizontally by a factor of 2 to obtain an ellipse what is the equation of this ellipse in general form?
Penny Nom lui répond.

Finding the vertical height of a roof 2007-03-05

Zainab pose la question :
The question is: If the vertical height if a triangle is half the width of the base and the slant length is 6 metres, find the exact vertical height of this part of the roof. I'm actually confused about finding out the height of an equilateral triangle if you're only given the length or slant height. Please help! O.o
Stephen La Rocque lui répond.

Direct and inverse variation 2007-03-03

Rene pose la question :
Hi I'm Rene, I'm stuck with some problems in direct and inverse variation.

I know how to solve direct and inverse problems when only one variation is in a question at a time.

EX: p varies inversely as the square root of q, and when p=12, q=36 find p when q=16

12*6 =p*4
72=4p
18=p

But how would you solve a problem like.....

If s varies directly as r and inversely as t, and s=10 when r=5 and t=3, for what value of t will s=3 when r=4 ?
Penny Nom lui répond.

The intersection of two lines 2007-02-28

Tamara pose la question :
I was told to make a graph to help solve this question. I was given two equations. One was x-2y=3 and the other was 2x+y=-4. We have to change it to the equation of the line format. Then we graph the line and find the point where they meet. I've been trying to do that, but when i check the answer, It turns out wrong. It's meeting in the wrong spot. I need help please.
Penny Nom lui répond.

Find the nth term 2007-02-27

Dinky pose la question :
My teacher has set us a project, but i am having trouble finding the nth term for this. the numbers are: 1, 2, 6, 24, 120 could you please help me? thank you dinky113
Stephen La Rocque and Penny Nom lui répond.

Social security numbers 2007-02-27

Tish pose la question :
Social Security numbers are in the form ###-##-####, where each symbol represents a number 0-9, how many are possible with this format? Will we ever run out of Social Security numbers?

(This is one question with two parts, I saw some examples but I am still confused because if there are 1 million possibilities then how have we been able to issue out numbers to over 280 US citizens?) (For the second part a yes or no answer is sufficient)
Penny Nom lui répond.

Cutting the top off a circle 2007-02-25

Daniel pose la question :
If a circle as a diameter of D I cut off a straight part at C from the top What is the formula to find the area of the left over part?
Penny Nom lui répond.

Arithmetic Series 2007-02-18

Krista pose la question :
Question- The sum of the first 4 terms of an arithmetic series is -8 and the sum of the first 5 terms is 500. Determine the sum of the 3 terms.
Stephen La Rocque lui répond.

What is the index of the term '119' in the sequence 2, 5, 8, 11? 2007-02-16

joey pose la question :
What is the index of the term '119' in the sequence 2, 5, 8, 11?
Penny Nom lui répond.

The nth term 2007-02-13

Sarah pose la question :
I am having difficulty in finding the nth term for 7,49,343,2401. Could you please help me in finding the correct answer?
Stephen La Rocque lui répond.

The sum of a sequence 2007-02-11

joey pose la question :
find the sum of the first 98 terms of the sequence 3, 5, 1, 3, 5, 1, 3,
Penny Nom lui répond.

Piecewise Functions 2007-02-09

Steph pose la question :
h(x)={-2 if x<0
{x+1 if 0< x <10
{-1/2x+16 if x>10 PLEASE HELP
Penny Nom lui répond.

Find the next 3 terms of the sequence 2007-02-07

rose pose la question :
find the next 3 terms of the sequence 2,3,9,23,48,87
Penny Nom lui répond.

A triangle inscribed in a semicircle 2007-02-06

Benneth pose la question :
Consider a triangle inscribed in a semicircle with a radius of R. What are th possible perimeters for the triagle? And the areas?
Penny Nom lui répond.

A 3-digit number in base 7 has its digits reversed when expressed in base 9. 2007-01-28

Ashley pose la question :
A 3-digit number in base 7 has its digits reversed when expressed in base 9. Find this number.
Penny Nom lui répond.

The area of a ellipse 2007-01-25

Ranjit pose la question :
I have a task in which i have to find the area of a ellipse. i find this difficult because i have only been provided with the perimeter, which is 1000m.
Chris Fisher lui répond.

Line segments on dot paper 2007-01-21

Khaori pose la question :
The three line segments below are drawn on centimeter dot paper.

a. Find the length of each segment to the nearest ten-thousandth of a centimeter.
b. Could these line segments be arranged to form a triangle? If no, explain why or why not. If yes, answer this question: could they form a right triangle? Explain why or why not.
Penny Nom lui répond.

5,8,11,14,17 2007-01-18

Mairead pose la question :
the sequence i was given was 5,8,11,14,17 what is the nth term and what is the 10th term ?
Paul Betts lui répond.

Points of intersection 2007-01-18

Mark pose la question :
Find the points of intersection of the given pair of curves. 2x - 3y = -8 and 3x - 5y = -13
Steve La Rocque and Haley Ess lui répond.

An octagonal bird house 2007-01-13

Soren pose la question :
I'm in the process of building a birdhouse that is an octagon (based on previous questions, looks like that's a familiar tune). The essential elements are known, but I get stuck when trying to determine the angle for the cuts that would be made to the thickness of the wood so that they all fit together when assembled. Each octagonal section is 7 inches in width and the peak of the roof will be 2 inches higher than the sides. My sense is that the angle cuts that need to be made to the 'height' of each piece of wood. By height I mean the thinnest part of the wood that is neither the length nor the width to use colloquial terms. While it's clear that a slight angle is needed, it would seem that the angle would necessarily change as the distance from the top of any one side to the peak changes. Please advise if more clarification is needed. The 2 inches is random and can be changed if more convenient. Whew!
Harley Weston lui répond.

What is the percent of the decrease? 2007-01-10

Bill pose la question :
if the value of xyz company stock drops from $25 per share to $21 per share, what is the percent of the decrease?
Penny Nom lui répond.

Three consecutive odd integers 2007-01-08

Emma pose la question :
Find three consecutive odd integers such that the sum of the first and second is 27 less than 3 times the third.
Stephen La Rocque lui répond.

Twice the smaller of two consecutive integers is the larger increased by 5. 2007-01-08

Evan pose la question :
Twice the smaller of two consecutive integers is the larger increased by 5. find the integers.
Stephen La Rocque and Penny Nom lui répond.

13.78g /11.3mL 2007-01-05

Judd pose la question :
13.78g /11.3mL
Penny Nom lui répond.

How do I determine the length of an ellipse if the width and area are known? 2007-01-04

Tom pose la question :
How do I determine the length of an ellipse if the width and area are known?
Steve La Rocque and Karen McIver lui répond.

An octagonal birdhouse 2006-12-30

Verner pose la question :
I am building a octagon birdhouse,what degree would I cut each side of each piece of wood to assemble the birdhouse?
Penny Nom lui répond.

Percentage increase 2006-12-21

Wang pose la question :
The last week of a month a car dealership sold 12 cars. A new sales promotion came out the first week of the next month and the sold 19 cars that week. What was the percent increase in sales from the last week of the previous month compared to the first week of the next month?
Penny Nom lui répond.

Find the total distance the swing traveled before it stopped. 2006-12-17

Leah pose la question :
Rebecca's little sister liked for her to push her in the swing at the park. The other day Rebecca pulled the swing back and let it go. She would have kept pushing, but she suddenly saw a friend at the other end of the park. The swing traveled a total distance of 10 feet before heading back the other way. Each swing afterwards was only 80% as long as the previous one. Find the total distance the swing traveled before it stopped.
Penny Nom lui répond.

1, 3, 6, 10... 2006-12-15

Lisa pose la question :
What is the nth term for the sequence, '1, 3, 6, 10...' and could you say how you got the anwser.
Stephen La Rocque and Penny Nom lui répond.

The nth term 2006-12-15

Lisa pose la question :
I have worked out that the nth term for 1, 4, 9, 16 is n squared and 3, 5, 7, 9 is 2n - 1, so what is the rule for the sequence 1x3, 4x5, 9x7, 16x9?
Penny Nom lui répond.

The nth term 2006-12-14

Hepzibah pose la question :
what is the definition of nth term and n?
Penny Nom lui répond.

Base 5 2006-12-11

Shelley pose la question :
how do you convert decimal numbers to a given base for example 2,875 to base five?
Stephen La Rocque lui répond.

Sectors of a circle 2006-11-30

Maithreyi pose la question :
A circle of diameter 21m is divided into three sectors with central angles 60degree,120degree and 180degree. Find the area of each sector?
Stephen La Rocque lui répond.

Percentage increase 2006-11-29

Toya pose la question :
I have some statistics from year to year based on drug seizures.(units= lbs) e.g. in 2005 123lbs seized in 2006 1518lbs seized. now i worked out the percentage increase as to be in the thousands which from looking at the figures is correct however i don't want to say 1000% increase.

using another formula current- previous *100 I got 92%. what exactly does this 92% represent and how can i use this number when presenting my answers instead of using 1000 + %
Stephen La Rocque and Penny Nom lui répond.

An arithmetic series 2006-11-28

Jillian pose la question :
Find the sum of 21 terms of an arithmetic series that has an eleventh term equal to 30.
Penny Nom lui répond.

A geometric sequence 2006-11-28

Jillian pose la question :
Find x so that 2x, x + 5, x - 7 are consecutive terms of a geometric sequence.
Stephen La Rocque lui répond.

A problem involving logs 2006-11-26

Beth pose la question :
any help would be appreciated on how to solve without using the change of base formula for logarithms in the solution and check of the solution!!!

log256 (x) + log16 (x) + log4 (x) + log 2 (x) = 7/4
Stephen La Rocque and Penny Nom lui répond.

Arithmetic with base -2 2006-11-26

Yuva pose la question :
can we do arithmetic ,base -2. If yes, how and if not, why.
Stephen La Rocque lui répond.

The area of a semicircle 2006-11-25

Melinda pose la question :
If the radius of a semi-circle is 9ft what is the area?
Karen McIver and Penny Nom lui répond.

An Easement 2006-11-21

Ms Porter pose la question :
I need to acquire a 20 feet easement for a project and I need to know how many square feet are in a 20 feet easement?
Penny Nom lui répond.

The Fibonacci sequence 2006-11-21

Ross pose la question :
Let f0 = 0; f1 = 1,... be the Fibonacci sequence where for all n greater than or equal to 2 fn = fn-1 + fn-2. Let Q = (1+square root of 5)/2. Show that for all positive n greater than or equal to 0, fn less than or equal to Q^(n-1).
Penny Nom lui répond.

Conic sections 2006-11-19

Joyce pose la question :
My son has a project on conic sections. I need the following information on Parabola, Circle, ellipse,and hyperbola. He can't find the following information for each conic section: equations with explanations, four uses for each shape and Shape explanation.
Penny Nom lui répond.

On day 1 on which day will 96 students donate food? 2006-11-19

Veydee pose la question :
during a canned food drive the number of students who donate food doubles each day. If three students donate food on day 1 on which day will 96 students donate food? we have to find the term rule for this pattern
Penny Nom lui répond.

Induction 2006-11-16

John pose la question :
Find a formula for
1/(1x3)+1/(2x4)+1/(3x5)...+1/(n(n+2))
by examining the values of this expression for small values of n. Use mathematical induction to prove your result.
Penny Nom lui répond.

Sigma from 0 to infinity of (n^3 / 3^n) 2006-11-15

Cedric pose la question :
I'm wondering how you would find if this series converges or diverges?

Sigma from 0 to infinity of (n^3 / 3^n)

Does the n^3 dominate, or does the 3^n dominate? What about higher powers like n^10 / 10 ^ n ? Which one would dominate then?
Penny Nom lui répond.

The empty set is a subset of every set 2006-11-14

Narayana pose la question :
The empty set is a subset of every set
Stephen La Rocque and Penny Nom lui répond.

Some applications of conic sections 2006-11-13

Burt pose la question :
how are circles, ellipses, and hyperbolas used in everyday life
Penny Nom lui répond.

Piecewise functions 2006-11-08

Kait pose la question :
We discussed how to graph piecewise functions today and I'm very lost!! I'm sitting here staring at this problem that says:
f(x){2x+1, if x <1
f(x){-x+4, if x is greater than or equal to 1.
Penny Nom lui répond.

1,4,9,16,25,36..... 2006-11-06

Teje pose la question :
i cannot find the next number for this sequence 1,4,9,16,25,36..... could u help please
Stephen La Rocque lui répond.

The semester grade 2006-11-03

Caroline pose la question :
Can you tell me how to calculate a grade based on a percentage formula where 15 assignments account for 40% of the grade and 3 tests account for 60% of the semester grade.
Penny Nom lui répond.

Kilowatts and Horsepower 2006-11-03

Michael pose la question :
How many Kilowatts=1 Horsepower or Horsepower=1 Kilowatt?
Stephen La Rocque lui répond.

The sum of 2000 consecutive integers is 1000 2006-10-29

Matias pose la question :
if the sum of 2000 consecutive integers is 1000, then the sum digits of the greatest of these 2000 integers is?
Penny Nom lui répond.

Three consecutive integers 2006-10-29

Jimmy pose la question :
Basically i want to know how you prove that the product of any 3 consecutive integers is a multiple of 6
Stephen La Rocque lui répond.

The real numbers with decimal representations consisting of all 1s. 2006-10-29

Ivessa pose la question :
Determine if the following set is countable or uncountable : the real numbers with decimal representations consisting of all 1s.
Steve La Rocque and Walter Whiteley lui répond.

How many sequences are possible? 2006-10-28

Sam pose la question :
A fair eight-faced die with faces numbered 1,2,3,4,5,6,7 and 8 is tossed six times and the sequence of numbers is recorded. How many sequences are possible?
Penny Nom lui répond.

Direct and Inverse variation 2006-10-27

Vishalinee pose la question :
i'm not sure how to use the words direct variation and inverse variation to describe thre relationship between:

a. speed and distance
b.speed and time
c. distance and time.

and then i need to create equations using the descriptions. i am really messed up with direct and inverse variation.

Karen McIver lui répond.

Three consecutive odd numbers 2006-10-21

Pige pose la question :
The sum of three consecutive odd numbers is 387. Find the numbers.
Penny Nom lui répond.

A trillion seconds? 2006-10-16

A student pose la question :
How many years, days, hours, minutes, and seconds in a trillion seconds?
Stephen La Rocque lui répond.

Percentage increase 2006-10-15

Amanpreet pose la question :
in yr 7, bill was 1.28 m tall, in yr 9 he was 1.67m tall. calculate his percentage increase in height
Stephen La Rocque lui répond.

How many feet tall is the tunnel 2006-10-14

Charles pose la question :
A tunnel in the Smoky Mountains is semicircular. At a distance of 12 feet from the center of the tunnel, the tunnel has a height of 16 feet. How many feet tall is the tunnel at its center?
Penny Nom lui répond.

Plotting percentage change 2006-10-11

Beckie pose la question :
I have worked out a set of percentage differences which are all percentage decrease. Should i express them as a negative percentage as -20%? I also need to plot them on a graph and am not sure whether to just use the percentage difference as it is, in which case i get a positive gradient, or include a negative axis and plot them in this way, in which case i would get a negative gradient. I think the slope of the curve will be the same either way so it might not matter!
Penny lui répond.

One-quarter of all 3-subsets of the integers 1,2,3....,m contain the integer 5 2006-10-09

Hina pose la question :
If one-quarter of all 3-subsets of the integers 1,2,3....,m contain the integer 5, determine the value of m.
Steve La Rocque and Claude Tardif lui répond.

The area of an oval 2006-10-08

Bruce pose la question :
area of an oval: 60" x 120"
Stephen La Rocque lui répond.

How many line segments are necessary? 2006-10-04

Varun pose la question :
If you place 35 points on a piece of paper so that no three are collinear, how many line segments are necessary to connect each point to all the others?
Stephen La Rocque lui répond.

A number pattern 2006-10-02

Tim pose la question :
The patterns that went in 2s, 4s and 5s we got, but we are stuck on the pattern that doubles. We can't come up with the rule or equation that solves it.

With the first number being the term number and the second being the term, this is the pattern:

1-1
2-2
3-4
4-8
5-16
6-32
7-64
100-128

What is the rule for this?

Stephen La Rocque and Penny Nom lui répond.

The hypotenuse 2006-10-02

Ashley pose la question :
How do you find the hypotenuse of a right triangle? I don't understand how to find c.
Stephen La Rocque lui répond.

The focus of a parabola 2006-10-01

Lily pose la question :
I have a mathematical assignment which includes applications of parabolas, hyperbolas and ellipses in the real world. I have been searching the internet and now I am ware that most of the applications of parabolas have a connection with what people call "the focus". However, I do not think I clearly understand what "the focus" of a parabola is. Would you please explain it to me?
Penny Nom lui répond.

2 5 11 17 23 31 ? 2006-09-28

Bernice pose la question :
How do you determine the next number in the following sequence:
2 5 11 17 23 31 ?
Penny Nom lui répond.

Piecewise functions 2006-09-24

Claudia pose la question :
hi! i was just looking at a question by someone else about piecewise functions, but i still don't get it.
my problem is
g(x){x+2 if x <-2}
g(x){2x - 1 if x> or = -2}
Penny Nom lui répond.

Find the nth term 2006-09-13

Shakira pose la question :
my question is - Find an expression for the nth term of each sequence.

a. 6,15, 28, 45, 66

b, 1/5, 3/8, 5/13, 7/20, 6/29 - these are fractions

Penny Nom lui répond.

-5, 3, -2, 1, -1, 0, __, __ 2006-09-12

Sherrie pose la question :
next two terms in the sequence: -5, 3, -2, 1, -1, 0, __, __
Stephen La Rocque lui répond.

Brackets and more brackets 2006-08-29

Michelle pose la question :
Feeling stupid asking but it's been awhile ... {{{2}}} ...what is this really saying ....are the outer brackets = null?
Stephen La Rocque lui répond.

Points of intersection 2006-08-20

Gianella pose la question :
Find the points of intersection by solving this problem analytically.

y= x cubed
y= x

Stephen La Rocque lui répond.

Find the points of intersection 2006-08-18

Ingrid pose la question :
The question says find the points of intersection of the graphs of the equation, and check your results analytically.

x squared + y squared=25
2x+ y=10

Stephen La Rocque lui répond.

A concrete semicircle 2006-08-15

John pose la question :
I have to figure out how many yards of concrete I need for a semicircle. I have a radius of 21 feet and the concrete is 4" thick. I took 3.14 x (21)^2 then divided by 40 to get how many yards of concrete but that doesn't seem right.
Penny Nom lui répond.

Marking out a circle 2006-06-28

Peter pose la question :
given a straight line. how do i work out the off sets ( at right angles) at several intermediate points. to set out a 5.0m arc that has a 18.0m radius.
Stephen La Rocque and Penny Nom lui répond.

The area of a house 2006-06-28

Michael pose la question :
I would like to know how to measure the area of a house?
Penny Nom lui répond.

The area of a sector and a triangle 2006-06-23

Howard pose la question :
I thought of the following problem which is similar but much simpler than the tethered goat problem: What is the angle(it is more illustrative in degrees)of arc of a unit circle so that the area between the chord it subtends and the arc length is equal to the area of the triangle with opposite side the subtended chord.
Stephen La Rocque and Penny Nom lui répond.

As close to 841 as possible 2006-06-21

Alan pose la question :
using these numbers by either add subtract division multiply come up with the answer as close to 841
100 25 10 7 6 3
Paul Betts lui répond.

13 57 91 11 31 51 ?? 2006-06-15

Chastity pose la question :
im trying to determine the missing number in the sequence 13 57 91 11 31 51 ??
Claude Tardif, Steve La Rocque and Natasha Glydon lui répond.

The perimeter of a pool 2006-06-05

Troy pose la question :
How many Linear feet would a pool be if the pool was 18 by 38 foot oval
Penny Nom lui répond.

What is the value of csc (-2pi/3)? 2006-06-04

Kishor pose la question :
What is the value of csc (-2pi/3)?
Stephen La Rocque lui répond.

What is the sum of the first 100 whole numbers? 2006-05-31

Jo pose la question :
what is the sum of the first 100 whole numbers?
Natasha Glydon, Paul Betts and Penny Nom lui répond.

The area of part of a circle 2006-05-29

Larry pose la question :
need to find area of a circle between a given line (cord) to the circumference of the circle (see attachment). I often review blue prints of homes and many times have to know the area the home.
Stephen La Rocque and Penny Nom lui répond.

The nth term of a sequence 2006-05-24

A student pose la question :
please could you give me a formula for the following numbers for my teacher 3 8 15 24 35
Chris Fisher lui répond.

Three purses 2006-05-22

Marcee pose la question :
If you take $20 from the first and put it into the second of three purses, the second would then contain 4 times as much as remains in the first. If $60 of what is now in the second is put into the third, the third will contain twice what is in the first and second together. Now, if $40 be removed from the third and put into the first, there will be half as much as in the third. What did each purse originally hold?
Penny Nom lui répond.

We are 2 pairs of consecutive 2 digit numbers ... 2006-05-13

A perent pose la question :
We are 2 pairs of consecutive 2 digit numbers that are factors of the number of feet in a mile. Who are we?
Claude Tardif lui répond.

A person is given 3 true or false questions 2006-05-11

Larry pose la question :
A person is given 3 true or false questions. They have no idea of the answers. What is the probability of the person getting them all correct? Could you show me a tree for this.
Penny Nom lui répond.

Small pipes and large pipes 2006-05-09

geece pose la question :
A large fresh water reservoir has two types of drainage system. Small pipes and large pipes. 6 large pipes, on their own, can drain the reservoir in 12 hours. 3 large pipes and 9 small pipes, at the same time, can drain the reservoir in 8 hours. How long will 5 small pipes, on their own, take to drain the reservoir?
Penny Nom lui répond.

Adding consecutive numbers 2006-04-26

Lisa pose la question :
When I have a total that is the sum of consecutive numbers, how do I figure out what the numbers are?
Stephen La Rocque lui répond.

Geometric sequence and basic functions (graphs) 2006-04-20

Marlene pose la question :
Which of the basic functions is related to the geometric sequence: Linear, Quadratic, Rational, or Exponential? Can you give me an example of how it would be used in normal life?
Stephen La Rocque lui répond.

Arithmetic and Geometric Sequences 2006-04-19

Skye pose la question :
If the 1st, 4th, and 8th terms of an arithmetic sequence are consecutive terms in a geometric sequence, find the common ratio of the geometric sequence.
Stephen La Rocque lui répond.

Reverse percentage 2006-04-19

Mike pose la question :
How would I calculate a reverse percentage? Let me give you an example. I have two values that calculate to a success rate of 93.32. Total=1546051 Failures=103302. (1546051-103302)/1546051=93.32% success. Now how much would I need to increase the total value to get the success up to 95%?
Stephen La Rocque lui répond.

Overlapping area of two circles 2006-04-15

Jade pose la question :
Given two identical circles where the radius (6 units) is the distance between the centers, what is the area of the overlapping region?
Stephen La Rocque lui répond.

What is the cost price? 2006-04-14

Purushotham pose la question :
If the selling price is 120 and the profit is 20%, what is the cost price?
Stephen La Rocque lui répond.

The product of successive terms in sequences 2006-04-13

Forrest pose la question :
1) Find three successive terms in an arithmetic sequence such that their sum is 24 and their product is 440 2) Find three successive terms in a geometric sequence such that their sum is 21 and their product is 216
Penny Nom lui répond.

Finding the inverse of a function 2006-04-12

Sam pose la question :
If g(x) = 2x+3/5 then how do I find the inverse?
Walter Whiteley lui répond.

Arithmetic Sums 2006-04-12

Angel pose la question :
(a) In a particular arithmetic sequence, u6 = 344.5 and u20 = 88.3. Find S28. (b) In a particular arithmetic series, S10 = 495 and S15 = 1005. Express S15 in sigma notation.
Stephen La Rocque lui répond.

Sum of a Geometric Sequence 2006-04-11

Andre pose la question :
In a particular geometric sequence, U3=-3.6 and U10=12.9. Find S16 and S17.
Stephen La Rocque lui répond.

A plant increases its height by 1/2 the first day,... 2006-03-30

Andy pose la question :
A plant increases its height by 1/2 the first day, 1/3 the second day, 1/4 the third day and so on. How many days did it take to grow to 100 times its height?
Stephen La Rocque lui répond.

Can an equilateral triangle have an obtuse angle? 2006-03-26

Chris pose la question :
Can an equilateral triangle have an obtuse angle?
I'm thinking not, because all sides must be equal, but
does that also imply that all angles are equal?

Stephen La Rocque lui répond.

The cartesian product of a countably infinite collection of countably infinite sets 2006-03-25

Geetha pose la question :
Is the cartesian product of a countably infinite collection of countably infinite sets countable infinite?
Penny Nom lui répond.

How much fabric do I need? 2006-03-25

Michelle pose la question :
I AM DECORATING A STAGE FOR A BOARD OF DIRECTORS MEETING AND I NEED TO BUY FABRIC AND I DON’T WANT TO WASTE $$ BY BUYING TOO MUCH FABRIC OR NOT ENOUGH FABRIC.

THE AREA THAT I’M NEEDING MATERIAL FOR IS, 12ft HIGH BY 34ft WIDE.

THE FABRIC COMES IN ROLLS OF 60” (inches) x 100 yards.

SO HOW MUCH FABRIC SHOULD I NEED TO FOR THE AREA I’M WANTING TO COVER?

Stephen La Rocque and Penny Nom lui répond.

Piecewise functions 2006-03-21

Kris pose la question :
First Problem:
Southeast Electric charges .09 cents per kilowatt-hour for the first 200 kWh.The company charges .11 cents per kilowatt-hour for all electrical usage in excess of 200 kWh. How many kilowatt-hours were used if a monthly electric bill was $57.06? The answer I came up with is 360, is that right? and also how do I set it up in an equation form?

Second Problem:
A construction worker earned $17 per hour for the first 40 hr of work and $25.50 per hour for work in excess of 40 hr. One week she earned $896.75. How much overtime did she work? I came up with 8.5 hrs over-time worked. Again I don't know how to set up the equation to come up with the answer.

I need some pointers on how to figure out story problems! If you have any suggestions that would help me out I would be very grateful.
Penny Nom lui répond.

How far from Earth is Neptune? 2006-03-21

Scott pose la question :
A laser beam travelling at the speed of light bounces off the planet Neptune and returns to Earth in 29 960.72 s. The speed of light is 299 792.5 km/s. How far from Earth is Neptune?
Penny lui répond.

The square footage of an area in my backyard 2006-03-17

Kim pose la question :
I need to find out how to calculate the square footage of an area in my backyard that is in the shape of a "slice of pie". There are two sides that are straight lines that come together at the top to form a point, and then at the bottom is a curved line that joins the two other lines together. I need to figure out how to calculate the square footage that is inside the area.
Penny Nom lui répond.

Divide the product of three consecutive positive integers by their mean 2006-03-12

Sandy pose la question :
When I divided the product of three consecutive positive integers by their mean, I got 99. What is the smallest of the three numbers?
Stephen La Rocque lui répond.

Two consecutive even integers 2006-03-11

Cheryl pose la question :
Find two consecutive even integers that have a sum of 450
Stephen La Rocque lui répond.

How many of these cubes have no wax of them? 2006-03-10

Iban pose la question :
cube cheese is 4cm wide, 4cm long, 4cm high. three faces of the cube meet in the corner covers thin layers of wax. The cheese is then cut two, then cut 64 small cubes, which is the length 1cm. How many of these cubes have no wax of them?
Stephen La Rocque lui répond.

8,_,4,9,1,_,10,3,_,0 2006-03-08

Rachel pose la question :
I cant figure out this sequence if someone could help me 8,_,4,9,1,_,10,3,_,0
Claude Tardif lui répond.

A nine digit number 2006-03-06

Ryan pose la question :
What is the total number of possible combinations of a nine digit number (ie., social security number) including repeating numbers?
Stephen La Rocque and Penny Nom lui répond.

2,4,9,6,5,6,____,____,____,... 2006-03-06

Mike pose la question :
I am having problems figuring out the following sequence:
2,4,9,6,5,6,____,____,____,...

We were able to guess that the pattern simply started to reverse itself, but I was wondering if there were other possibilities.

Claude Tardif lui répond.

The nth term 2006-03-05

Umar pose la question :
my question is what is the nth term for a house of cards 4 stories high if you use the following numbers:
2 7 15 26
Penny Nom lui répond.

A 5900% increase 2006-03-03

Pat pose la question :
I want to find out the % of production increase from 250 dolls a month to 15,000 dolls a month. i think it is 5900% but that seems too high.
Penny Nom lui répond.

A cone with an oval as base 2006-03-01

Richard pose la question :
I am trying to find the volume of a cone that is not round but oval.
Penn Nom lui répond.

Luke and Slim have only one horse. 2006-02-26

Emily pose la question :
Luke and Slim have only one horse. Luke rides for the agreed on distance and then ties up the horse for Slim, who has been walking. Meanwhile, Luke walks on ahead. They alternate walking and riding. If they walk 4 miles per hour, and ride 12 miles per hour, what part of the time is the horse resting?
Penny Nom lui répond.

The nth term of a sequence 2006-02-21

Mike pose la question :
I'm having trouble finding the nth term in an equation, can you help me?
Stephen La Rocque lui répond.

Percent gain 2006-02-14

Bill pose la question :
If a stock is bought at $3.50 and sold at $5.80, what percent was the gain?
Penny Nom lui répond.

Find two consecutive integers whose product is 182 2006-02-09

Anthony pose la question :
Find two consecutive integers whose product is 182
Steve La Rocque lui répond.

The intersection of a line and a circle 2006-02-02

Bernice pose la question :
if i am given an equation of a circle and 2 points in a line how do i know if the line intersects the circle and how do i determine the points of intersection
Chris Fisher lui répond.

Arithmetic progressions 2006-01-31

A student pose la question :
1)the sum to n terms of a particular series is given by S_n=17n-3n²

a)find an expression for the n term of the series
b)show that the series is an arithmetic progression

2)a particular arithmetic progression has a positive common difference and is such that for any three adjacent terms ,three times the sum of their squares exceeds the square of their sum is 375.Find the common difference

Penny Nom lui répond.

An array problem 2006-01-31

Cynthia pose la question :
Write a number sentence for this array........

It's a rectangle box 3 down and 4 wide.

Penny Nom lui répond.

Percentage increase in sound intensity 2006-01-29

David pose la question :
I am doing some emotion response mapping. Being a composer I know how to push the heart beat tempo by a % increase of BPM in my music. I want to know how to calculate an increase in intensity of sound. Now I have 60 decibels. I want an increase of intensity by a factor n% with out going over 156 decibels.
Penny Nom lui répond.

how can i find the height of a triangle if i have the base and the hypotenuse 2006-01-27

Kelsey pose la question :
how can i find the height of a triangle if i have the base and the hypotenuse
Penny Nom lui répond.

Sectors and arcs 2006-01-25

Wael pose la question :
How is the area of an arc (alpha*pi*r squared/360) derived?
How is the length of an arc (alpha*pi*r/180) derived?
Penny Nom lui répond.

Finding the nth term in fractions 2006-01-23

Zarina pose la question :
Each term in this sequence is made by increasing the numerator by 1 and the denominator by 3. here are the first five terms:

1/4, 2/7, 3/10, 4/13, 5/16, ...

(a) write an expression for the nth term:
Penny Nom lui répond.

A sequence of circles and tangents 2006-01-16

Paul pose la question :
Consider a circle whose center is (2,2) and whose radius is 1, and the straight line that goes through the origin and that is tangent to this circle so that the intersection between them is as shown in the attached picture. With this new point we make a new circle whose radius is half of the first one, and we calculate the corresponding intersection point with the same suppositions as in the first case. We repeat the process to the infinite. Find the distance between the center of the circle in the infinite and the origin (point (0,0)).
Chris Fisher lui répond.

Percentage change when you start from zero 2006-01-02

Joseph pose la question :
I am not sure if my meaning for calculation for a percent change (C-P/P)x100) is correct. In this case, C=10, P=0, does this mean 100 percent increase from previous period?
Harley Weston lui répond.

The area of a sector of a circle 2006-01-02

Natashia pose la question :
How do you find the area of a shaded sector of a circle?
Penny Nom lui répond.

Joey had 8 drinking glasses, all of different sizes. 2005-12-29

Danielle pose la question :
Joey had 8 drinking glasses, all of different sizes. he has lined them up from smallest to largest and numbered them #1 (smallest) to #8 (largest). he knows that glass #4 holds 10 ounces and that glass #7 holds a pint, or 16 ounces. Now he wants to figure out how much all the others hold!

He experiments by filling up different glasses with water and pouring the water back and forth into other glasses. Her are his results:
Penny Nom lui répond.

Percent change 2005-12-17

Marie pose la question :
What is the percentage change when 1500 becomes 2000?
Penny Nom lui répond.

Percentage increase 2005-12-15

Luiz pose la question :
I would like to know how much net income in % we have increased from 2005 to a 2006(projection).
2005 Net Income Actual: $1,599,887
2006 Net Income Budgeted: $2,067,339
Penny Nom lui répond.

Find the nth term 2005-12-14

Kevin pose la question :
How do i find the nth term of 1 4 9 16 25 36
Penny Nom lui répond.

The stair problem 2005-12-06

Arnold pose la question :
My daughter had me help her with some of her college math problems that require finding the pattern. The problem was the stair problem where you can climb either 1 step or 2 steps at a time. How many combinations are there to get to the 10th step. I found the data set that solves the answer to the question, but is there an equation that expresses the answer in terms of n?

1 2 3 4 5 6 7 8 9 10 stair number
1 2 3 5 8 13 21 34 55 89 number of possible combinations

Harley Weston lui répond.

An Arithmetic sequence 2005-12-01

Aana pose la question :
The first term in an arihmetic series is 25 and the 3rd term is 19. Find the number of terms in the series if its is 82.

Here's what I did to find d
a+2d=19; 25+2d= 19 ;19-25=2d d=-6/2=-3

This is where I'm stuck. Can you please provide me with some guidance.

Penny Nom lui répond.

The sum of n consecutive integers 2005-11-27

Craig pose la question :
If 875 is expressed as the sum of n consecutive integers (n > 1), then the number
of possible values of n is?

Possible Answers:
A) 15
B) 8
C) 7
D) 16
E) 4

Penny Nom lui répond.

Notation for the second derivative 2005-11-08

Mussawar pose la question :
my question is ^d/_dx( ^dy/_dx) = ^d²y/_dx². why it is not equal to ^d²y/_d²x.
Penny Nom lui répond.

How many passengers boarded the plane in Phoenix? 2005-11-03

Vish pose la question :
Passengers boarded a plane in Phoenix. In Dallas 1/2 of the passengers got off and 4/5 of the original number got on. In Memphis 3/4 of the passengers got off and twice the number of remaining passengers got on. In Chicago 2/3 of the passengers got off the plane leaving 39 passengers. How many passengers originally boarded the plane in Phoenix?
Penny Nom lui répond.

A tangent to a parabola 2005-11-02

A student pose la question :
Find the point on the curve y=x² where the tangent to the curve is parallel to the secant line connecting (-1,1) and (2,4)
Penny Nom lui répond.

2, 6, 12, 20, 30, ... 2005-11-01

Rebecca pose la question :
I have a sequence of I have a sequence of 2, 6, 12, 20, 30, and have no idea how to figure out the nth term please help!
Claude Tardif lui répond.

The area of an irregular semi-circle 2005-10-14

Bob pose la question :
Is there a way to compute the area of an irregular semi-circle i.e. one in which the arc length is not determined by the diameter; and is therefore not technically any part circular - yet still possessing an arched side?
Penny Nom lui répond.

Calculer la clé 2005-09-29

Un eleve pose la question :
Chaque individu a un numéro INSEE de 13 chiffres auquels est adjointe une clé de deux chiffres. voici comment est calculée cette clé :
Claude Tardif lui répond.

Open dots and closed dots 2005-09-29

Cynthia pose la question :
When graphing the solutions of an inequality, what is the difference between an open dot and a closed dot?
Penny lui répond.

Find the next 5 terms 2005-09-24

Grant pose la question :
n+7, 2n-0.5, 4n. Find the next 5 terms of each one and explain the sequence in words
Penny Nom lui répond.

Converting from base ten to base five 2005-09-21

Julie pose la question :
My sister is home schooled and we are trying to convert from base 10 to base 5. We are trying to teach and we have never had this in school. If we could have some examples of some problems and how to do them we would appreciate this.
Penny Nom lui répond.

Percentage increase 2005-09-19

Dory pose la question :
Last year sales was 120,000 $ and this year sales is 280,000 $, there was an increase in sales. what I would like to know is the percentage increase between the years with the formula.
Penny Nom lui répond.

A 3-dimensional pie shape 2005-09-17

Bill pose la question :
Your site appeared in my search for the name of a 3-dimensional pie shape. 2-d would be a sector of a circle. As it it curved, I don't believe it is in a the polyhedra family. Can you help me find the mathematical term for it?
Chris Fisher lui répond.

Find the first five terms of this sequence? 2005-09-17

Jade pose la question :
my homework says can you find the first five terms of this sequence? 5n-6 i can`t figure it out.
Penny Nom lui répond.

Elliptic trigonometry 2005-09-15

Krystal pose la question :
I'm currently searching for a science project topic and i have the idea of deriving elliptic trigonometry analogous to circular trigonometry. My questions are: Is this project "possible" to do?
Chris Fisher and Harley Weston lui répond.

A piecewise function 2005-09-15

Duncan pose la question :
A child is assigned to your care and she has a headache. The parent has authorized the administration of Children's Tylenol. Read a box of Children's Tylenol (or any other similar drug) and find the directions for administration. Note the child's weight and the corresponding dosage. (Be sure the drug you choose has a minimum of 4 weight intervals.)
Penny Nom lui répond.

Finding the nth term 2005-09-12

Paul pose la question :
Hi , Im having a problem helping my daughter to find the Nth Term in the following sequences.

1/3 1/2 3/5 2/3

and

1 3 6 10

Penny Nom lui répond.

The sum of a series 2005-08-31

Aamod pose la question :
Find the sum of the given series till n terms:

(1⁴\1*3) + (2⁴\3*5) + (3⁴\5*7)............... till n terms
Chri Fisher lui répond.

1,4,9,1,6,2,5,3,6,4,9,6,4,8,1 2005-08-30

Liz pose la question :
Find the next four numbers to the sequence 1,4,9,1,6,2,5,3,6,4,9,6,4,8,1,___,___,___,___.
Penny Nom lui répond.

cos x * cos 2x * cos 4x * cos 8x 2005-08-29

Leandro pose la question :
A = cos x * cos 2x * cos 4x * cos 8x

What's the value of log A at base 2?

Chris Fisher and Penny Nom lui répond.

y = log(x) + x. Solve for x. 2005-08-26

Alain pose la question :
I have the following equation:

y = ln(x) + x

How do I solve for x?

Penny Nom lui répond.

Is this percentage change or percentage increase? 2005-08-15

Betty pose la question :
When calculating a percentage, if the formula is A(new) - B(old)/A(new) Is this percentage change or percentage increase?
Penny Nom lui répond.

The Maclaurin series generated by f(x)=x^ cosx + 1 2005-08-10

Latto pose la question :
f(x)=x³·cosx + 1. but when I take the derivatives, I couldn't see a pattern. Can you help?
Penny Nom lui répond.

The equation of an ellipse 2005-07-17

Allan pose la question :
I working on a problem that asks me to give the equation of an ellipse when only the location of the directrix and the length of the latus rectum are given. No other points on the ellipse are given. Again, the only "givens" are:

Length of latus rectum = 12
Location of directrix is x = 16

If I could determine the eccentricity, I could proceed from there by taking the ratio of the distance from a focus to the latus rectum point to the distance of the point from the directrix, but I lack the x coordinate of c. I've searched the text, and feel I've "missed something" somewhere! I note that the latus rectum segment is unique in one respect in that it is parallel to the directrix, where any other line segment on the ellipse to the focus would not be. Please indicate where I'm going wrong.
Chris Fisher lui répond.

A lighthouse is located on a small island,... 2005-07-14

Brittnee pose la question :
A lighthouse is located on a small island, 3 km away from the nearest point P on a straight shoreline, and its light makes four revolutions per minute. How fast is the beam of light moving along the shoreline when it is 1 km from P?
Penny Nom lui répond.

Percent change 2005-07-01

Betty pose la question :
Can you tell me the difference between Percentage Change, Percentage Increase, Percentage Difference and please give an example of each, I am very visual.
Penny Nom lui répond.

A geometric sequence 2005-06-21

A student pose la question :
The first three terms of a geometric series are 3(q+5), 3(q+3), (q+7) respectively.
Calulate the value of q.

Penny Nom lui répond.

The circumference of an oval pool 2005-05-18

John pose la question :
I have an oval pool of which I am trying to find the circumference. it is 38 feet long and 19 feet wide
Penny Nom lui répond.

Angle of incline 2005-05-15

Kyle pose la question :
What is the degree of incline of a 12 foot plank that goes from 10.5 inches on one end to zero inches on the other?
Penny Nom lui répond.

Adding consecutive integers 2005-05-13

Yas pose la question :
i need some help with my work which is to investigating sums of consecutive numbers for example: 15= 4+5+6 and 15=1+2+3+4+5
Penny Nom lui répond.

A 5% increase 2005-04-27

Debra pose la question :
How can I determine the increased percentage of a dollar amount? I.e.: One dollar amount is $202 and another is $150, how can I determine the 5% increase from last year on the $202 dollar amount?
Claude Tardif lui répond.

The least integer of a set of consecutive integers 2005-04-19

Lucia pose la question :
The least integer of a set of consecutive integers is -25. If the sum of these integers is 26, how many integers are in the set?
Penny Nom lui répond.

Percentage increase 2005-04-19

Tom pose la question :
What is the percentage increase from (negative -$9262.00) to (positive $3840.00)?
Penny Nom lui répond.

A Taylor series for ln(x) 2005-04-16

Anood pose la question :
i have to represent ln(x) as a power series about 2
i`m not getting the final answer which is ln 2+ sigma (((-1)⁽ⁿ⁺¹⁾/ (n*2ⁿ))*(x-2)ⁿ). i don`t get the ln 2 part

i show you my trial

f(x)= ln x.

f-(x)=(1/x) .

f--(x)= (-1/x²)*1/2!

f---(x)= (2/x³)*1/3!

f----(x)= (-6/x⁴)* 1/4!

so the pattern shows me that f(n)= ((-1)⁽ⁿ⁺¹⁾)/xⁿ *n)

so f(2)= sigma ((-1)⁽ⁿ⁺¹⁾)/2ⁿ *n) *(x-2)ⁿ

so as you see i don`t get ln 2

Penny Nom lui répond.

Two overlapping circles 2005-03-20

Safi pose la question :
I have a problem to calculate the area of two overlapping circles because two circles are overlap then how i calculate the overlap area to subtract from the area of both circle.
Penny Nom lui répond.

Dimensions of a roof 2005-03-18

A roofer? pose la question :
A right triangle (roof of a house) has a base of 7 feet and a 22 degree angle. What is the height of the roof and what is the hypothenus of the triangle.
Penny Nom lui répond.

Biodiesel 2005-03-08

William pose la question :
My son is doing an demonstration for science class about how to make biodiesel. we are having problems with the conversion. for instance we think there are approx 190 liters in 50 gallons. Is this correct? Also if you needed 3.5 grams of lye per liter, would that be 662g of lye.
Penny Nom lui répond.

Spraying roses 2005-03-03

A student pose la question :
A litre and a half of water has 0.045 grams of herbicide added for spraying roses. How many grams of herbicide per litre is this?
Penny Nom lui répond.

Reverse pecentage 2005-03-01

Nathan pose la question :
Question for you. If I have spent $10.00, what is the mathamatical equation to
figure out what the G.S.T (7%) was?
Also if I were to spend $80.00 on a hotel, and I would like to know how much
G.S.T (7%) and how much provincial tax (6%) I spent how would I go about this.

Penny Nom lui répond.

A countably infinite collection of countably infinite sets 2005-02-26

Feroz pose la question :
Suppose a set can be divided into a countably infinite number of countably infinite sets.Then can the original set be considered as a countably infinite set?
Penny Nom lui répond.

Each interior angle of a particular polygon is an obtuse angle... 2005-02-22

Victoria pose la question :
Each interior angle of a particular polygon is an obtuse angle which is a whole number of degrees. What is the greatest number of sides the polygon could have?
Walter Whiteley lui répond.

arcsech x 2005-02-10

Monica pose la question :
Prove that arcsech x = ln[(1 + (1-x²)^(1/2)) / x ]
Penny Nom lui répond.

A seating arrangement 2005-02-03

Kay pose la question :
If you have 5 married couples, how many arrangements can be made if they must sit across from each other?
Penny Nom lui répond.

A line segment connecting two vertices of a polygon 2005-02-02

James pose la question :
What is a line segment (not a side) connecting two vertices of a polygon called?
Penny Nom lui répond.

Sum to n terms of the series i.(2^(n-i)) 2005-01-28

Satya pose la question :
Sum to n terms of the series i.(2^n-i)
Penny Nom lui répond.

Quadratics 2005-01-05

Usman pose la question :
Hi, in my Grade 11 Functions math class we have been assigned the task of finding jobs and careers related to quadratics, I have done many searches but have been unsuccessful, then I saw your website and e-mailed. I also have to use an example of a math problem that the job uses, then solve it, this will all compile on bristol board for a presentation. I would greatly appreciate it if you could send me some links and references of sources that refer to this subject.
Harley Weston lui répond.

An elliptical table 2005-01-03

Roger pose la question :
Want to make an elliptical table, say the long (major) axis is 4 feet, and the short (minor) axis is 3 feet. I can construct this figure, but I'm trying to figure out what the exact dimension of a rectangle within this ellipse will be if I make the table a drop leaf type where the drop dimensions are equal for each end of both the long and short axes. Intuitively, it looks like there is one and only one solution.
Penny Nom lui répond.

A line from the center of the patch to the periphery 2005-01-01

Sandrine pose la question :
I am currently researching a patch disease of grasses. These patches are roughly circular. I need a term for a line from the center of the patch to the periphery. Since the patches are not perfectly circular, my supervisors tell me I cannot use the word 'radius'. What else could I use?
Denis Hanson and Harley Weston lui répond.

An arithmetic progression 2004-12-24

A student pose la question :
the 4th and 5th term of an arithmetic progration 47 and 52 respactively find
a)d
b)a1
c)a50
Penny Nom lui répond.

Irrigation and a sector of a circle 2004-12-23

Chuck pose la question :
A friend of mine is a farmer and uses Pivots to irrigate portions of his land. The crop rows are in straight lines that all form chords of a large circle. The intent is to determine area between any two "boundary" rows expressed in acres.
Harley Weston lui répond.

The gradiant of a hill is 9% 2004-12-18

Jim pose la question :
The gradiant of a hill is 9%. What angle is created by the run/rise of the hill and 0 degrees?
Penny Nom lui répond.

Two intersecting lines 2004-12-18

James pose la question :
Imagine a vertical line 1.107' tall. Leaving the top of this line, sloping down to the right at a 4:1, at what horizontal distance will the line strike a second line, which leaves the the bottom of the vertical line sloping down to the right at a rate of .02 ft/ft (or 2%)? There is a fairly easy solution to this, but I have lost my notes!
Harley Weston lui répond.

A sequence 2004-12-11

Amanda pose la question :
Find the nth term of the following sequence

4, 10, 28, 82
Penny Nom lui répond.

Geometric sequence 2004-12-04

Lesa pose la question :
Find a formula for the geometric sequence: (√3 - √2), (4 - √6), (6√3 - 2√2), …
Penny Nom lui répond.

Cost before the markup 2004-11-23

Norman pose la question :
the sum of eg $130 includes the markup of 30%. However I need to calculate the percentage to apply to the $130 to assess the cost ie $100.
Penny Nom lui répond.

Proof by induction 2004-11-20

Vic pose la question :
Problem: Find the first 4 terms and the nth term of the infinite sequence defined recursively as follows:

a(1) = 3 and a(k+1) = 2a(k) for k -> 1.

Note: Quantities in brackets are subscripts
-> means 'equal to or greater than'.

Using the recursive formula, the first 4 terms are; a(1) = 3, a(2) = 6, a(3) = 12, a(4) = 24

The nth term a(n) = 2n-1 x 3 (equation 1)

Equation 1 must be proven using mathematical induction. This is where I am having a problem.
Penny Nom lui répond.

A sequence 2004-11-19

Liucy pose la question :
Find the Nth term: 10 40 90 160 250
Penny Nom lui répond.

A 40% reduction 2004-11-10

Cathy pose la question :
I'm having trouble figuring out how to figure a percentage??? it's easy to find what 40% of any given number is, but how would i accurately figure out what is the final number is when i know the number after the 40% has been removed? when i add 40% to this number it obviously is lower than it should be. the best i could figure is; x=?-40% ---------------> x-?=-40% i'm all confused????
Penny Nom lui répond.

The points of intersection of two graphs 2004-11-05

Benjamin pose la question :
How do I find the points of intersection of the two functions:
1) y =
2 - e-x 2) y = 1 + x2
Harley Weston lui répond.

A 40% increase in garage space 2004-10-20

Dianna pose la question :
A bus company recently expanded and no longer has enough room in its garage for all of its buses. Twelve of the buses have to be stored outside. If the company decides to increase their garage space by 40%, this will give them enough room for all of their current buses, plus enough room to store another twelve in the future. How many buses does the company own?
Penny Nom lui répond.

The third derivative 2004-10-15

Holly pose la question :
Why would you ever take the third derivative?
Harley Weston lui répond.

Direct and inverse variation 2004-10-05

Abraham pose la question :
Given that y varies inversely as x and x varies directly as z.If z is doubled then y is halved.Why is that true.Please explain.I'm having trouble understanding the different types of variation
Penny Nom lui répond.

1,3,6,11,18,29,__ 2004-09-21

Guillermo pose la question :
How do you get to the answer of this sequence 1,3,6,11,18,29,__
Claude Tardif lui répond.

f(x) = x-4 if x<2 2004-09-21

Dani pose la question :
Hi, my name is Dani. I'm in tenth grade Algebra 2, and I'm learning about a lot of different kinds of functions, and I can't quite seem to understand how every part of the piecewise function works. I understand most of it, I think, but I've been looking at an example in my math book, and I'm not sure how they got the answer they did. The part I don't understand reads: "Graph f(x) = x-4 if x<2" and "Identify the domain and range." The picture in the book shows an open circle at (2,-2), with an arrow going down and to the left with the slope being one. How did they get the open circle to be at (2,-2), and why does the arrow point where it does?
Penny Nom lui répond.

B={A,{A}} 2004-09-20

Muhammad pose la question :
Let A be a set and let B = {A,{A}}.

(a) Explain the elements of set B (with some example)

(b) Prove that A is not a subset of B.
Penny lui répond.

The hypotenuse of a right triangle 2004-09-20

Shannon pose la question :
I am trying to find the hypotenuse of a right triangle with only the length of the opposite side. What is the formula as I don't have the length of the adjacent side? Can I compute it without knowing what the other two angles are?
Penny Nom lui répond.

Perimeter and area of a semi_circle 2004-09-18

A student pose la question :
I want to know how to find the perimeter and area of a semi-circle and a quarter-circle.
Penny Nom lui répond.

A challenge 2004-09-17

Lasse pose la question :
xy
xx
xyx
xxx
xyxx

"x" and "y" each represents a number. Find out the system to make the next line
Penny Nom lui répond.

The length of a cut 2004-09-17

Florita pose la question :
My daughhter, who is a 9th grader is attempting to cut a piece of wood after determining the length of the cut for the hypotenuse. These are the measures: a=4squared, b=6squared.

She determined that c should equal 52. But when she measured the actual piece to be cut, c measured 39.5 inches! Can you offer any insight as to what she is doing wrong? I have suggested that she may be working with an Acute rather than a Right angle . But she insists that it is a Right angle after using a "framing square".
Claude Tardif lui répond.

1+3+5+...+(2n+1) 2004-09-10

Emma pose la question :
Prove that 1+3+5+...+(2n+1)= (n+1)²
Penny Nom lui répond.

An inverse 2004-09-09

Hillary pose la question :
I cannot figure out the inverse of this function.
f(x)= 1/2x -1
Penny Nom lui répond.

The nth term 2004-09-08

Alex pose la question :
What is the nth term?... Like what is it?, How do I find it?, and how exactly is used?...
Penny Nom lui répond.

d varies inversely with g 2004-09-07

Ashlyn pose la question :
d varies inversely with g when d=-8 and g=2 a. write d as a function of g using function notation. b. find d(10).
Penny Nom lui répond.

The intersection of planes 2004-09-07

Joshua pose la question :
I was wondering about the intersection of planes. Can planes intersect?
Penny Nom lui répond.

Nine minutes 2004-09-02

A student pose la question :
You have two hour glasses-one measures 7 minutes and one measures 4 minutes.How can you time 9 minutes?
Penny Nom lui répond.

The radius of a circle 2004-08-24

Peter pose la question :
If you slice any circle with a line, and call the distance of the line between intersections the "y" length and the perpendicular length to the shorter side of the curve the "x" length, what is the resulting equation for the radius?
Penny Nom lui répond.

The series from i=1 to n :ai 2004-08-18

Ken pose la question :
a.) Explain the difference between
the series from i=1 to n :ai
and the series j=1 to n :aj

b.) Explain the difference between
the series from i=1 to n:ai
and the series from i=1 to n :aj
Penny Nom lui répond.

The intersection of two graphs 2004-07-28

JJ pose la question :
Is there a way to find the intersections of these graphs algebraically?

x^2 + y = 4 & 2x - y = 1

I got (1.45, 1.9) and (-3.45, -7.9) with a graphing calculator.

AND THESE...

y = 3.29x & y = 5.5(x^0.5)+ 10000

I got x at 3133 with a graphing calculator.
Penny Nom lui répond.

The railing around a pool 2004-07-26

Bob pose la question :
I have a 15' circular above ground pool. Around the perimeter of the pool are eleven (11) sections of railing. Each rail has 5 slots at each end for pins. I have calculated that the length of the arc under the railing to be 51.4". what I am trying to determine is the distance between the end points of the arc so that I can figure out which slot to use in the rails without going round and round the pool moving and removing the rails until they finally fit. Been there, done that, no fun.
Penny Nom lui répond.

The inverse of a quintic function 2004-07-22

A student pose la question :
I'm really having trouble finding out the inverse of this quintic equation. F(X)= X⁵+3X³+1.I know that this quintic has an inverse because it is one to one. But I can't find a method to solve this. Finding the inverse of a quadratic or a cubic equation is a lot easier, but with this quintc I am really lost. I even know how the graph of this equation and its inverse looks like, but I'm not sure if Iam getting the right equation. Please help me out.
Penny Nom lui répond.

The number of blocks in a mile 2004-07-18

Valerie pose la question :
I don't know if you can help me but I was wondering how many blocks are in a mile in Ocean City, New Jersey?
Penny Nom lui répond.

Two puzzles 2004-07-13

Fred pose la question :
A young man's car developed a flat tire while he was driving along a deserted street. He pulled over to the curb and did all the usual things; removed the hub cap; unscrewed the lugs and rested them carefully in the hub cap, jacked up the car. As he was putting the spare tire onto the axle he accidentally kicked the hub cap. The lugs rolled out, and all five of them rolled down a nearby grate. Peering through the bars of the grate the man thought he could see the lugs about 6 feet below in a shallow water puddle. He had a problem, how do you think he solved it?

It is noon, your lunch hour, but you can not go out because there is a terrific hailstorm. Turning on your radio you hear the weathercaster predict that the hail will change to rain and that it will pour all day today. How can you determine the sun will be shining in 36 hours? Justify your answer.
Penny Nom lui répond.

An Octagonal playhouse 2004-07-13

Levi pose la question :
I'm building an octagon playhouse for my son that is 8 feet wide. what would be the measurements of each of the eight sides.
Harley Weston lui répond.

Choosing 5 numbers from 1,...,36 2004-06-30

A lottery player? pose la question :
how many combinations are there for the numbers 1thru 36 when only using each number once in groups of five
Penny Nom lui répond.

Jack's social security number 2004-06-08

A student pose la question :
Jack's social security number contains each of the nonzero digits exactly once. By examining the digits from left to right, he also found that 1 divides the first digit evenly, 2 divides the sum of the first two digirs evenly, 3 divides the sum of the first three digits evenly, and so on, until 9 divides the sum of all the digits evenly. What is Jack's social security number?
Penny Nom lui répond.

The base of a triangle 2004-05-25

Ralph pose la question :
With a 30 degree angle at the top of a triangle and a height of 15 what is the base?
Penny Nom lui répond.

Programming without trig functions 2004-05-25

Derek pose la question :
I am a programmer trying to calculate the following.

What is the formula to find the cross-sectional area of a cylinder with out using any trig functions? or better yet, how can you calculate any given volume in a cylindrical tank with spherical heads with out trig functions?

I am using a PLC (programmable logic controller) to do this and trig functions are not available.
Harley Weston lui répond.

Setting up an equation 2004-04-30

Matt pose la question :
I am trying to determine the dimensions of a 22 megapixel digital camera chip that has a 3:2 ratio. We know then, that: 3x = 2y (or 1.5x = y)

and that

xy = 22

Beyond this, I don't know how to hook those 2 seemingly unrelated facts together.
Penny Nom lui répond.

The sum of 4,0,-4..., -156 2004-04-28

Christina pose la question :
find the requested sum of the arithmetic sequence

4,0,-4..., -156
Penny Nom lui répond.

Related rates and baseball 2004-04-26

Bethany pose la question :
A baseball diamond is the shape of a square with sides 90 feet long. A player running from second to third base at a speed of 28 feet/ second is 30 feet from second base. At what rate is the player's distance from home plate changing?
Penny Nom lui répond.

A geometric sequence 2004-04-13

Michael pose la question :
In a geometric series, the sum of the 2nd and 3rd terms is 60, and the sum of the 3rd and 4th terms is 240. Find the sum of the first 7 terms.
Penny Nom lui répond.

What is the nth term 2004-04-07

Jason pose la question :
1 4 10 20 35 56 84
what is the nth term
Claude Tardif lui répond.

Trisecting an arbitrary angle 2004-04-06

Joe pose la question :
Where can I submit my effort on trisecting an arbitrary angle with only a straightedge and a compass? I can do it but I do not have the smarts to prove it.S
Chris Fisher lui répond.

The intersection of two graphs 2004-03-31

Benjanim pose la question :
How do I find the points of intersection of the two functions:

1) y = 2 - (e^-x)
2) y = 1 + (x^2)

I know that I have to set them equal to each other, but I can't solve for x. Please help :-)
Penny Nom lui répond.

The degree sequence of a graph 2004-03-31

Ali pose la question :
How can i find out {6,6,5,5,5,3,2}is not the sequence of the points of a simple graph,without drawing it?
Penny Nom lui répond.

Sections, area and acres 2004-03-23

Tony pose la question :
An acre , it can be any size right . so when they refer to a section of a township which is 640 acres, also 1 square mile does this mean that 1 sections length if sqaure and there is 5,280 ft in 1 mile does it meanthat if you took 1 side of the square of of 4 sides the lenth would be 5,280 feet long and by multiplying 5,280 x 5,280 it would give you the square mile in square feet. i guess what I 'm asking is what is the perimeter of 1 acre if it was shape like a square. sorry to make this confusing but if you can help I would appreciate it.
Penny Nom lui répond.

What's the next term? 2004-03-22

Garrett pose la question :
A friend hit me with these questions and won't tell me the answer nor how... please help? I've racked my brain and did all sorts of formulas, but I can't get it to work out... please...

What's the next number in this series... 5, 12, 17, 29, 46, ?

And this series... 12, 19, 28, 39, 52, 67, ?

and these... ocoa, boco, oboc, dobo, odob, ?

Claude Tardif lui répond.

Baseball games 2004-03-14

Fabian pose la question :
Let's say I have 12 different Baseball games. There is one of only 2 possible outcomes for each of the 12 games. How would I fugure out how many combinations there are for the 12 games and for 11,10, and so fourth.
Penny Nom lui répond.

Equivalent sets 2004-03-06

A student pose la question :
If A=(1,2,3,4,...) and B=(5,10,15,20,...), is A equivalent to B. Why or Why not ?
Penny Nom lui répond.

Cosine of 35 degrees 2004-03-03

Jason pose la question :
How do you find the exact solution to cosine 35 degrees.
Chris Fisher lui répond.

An elliptic cone 2004-02-24

Ben pose la question :
I am building a model for my architecture class. I need to build a elliptic cone out of chipboard and i have no idea how to do this.

The cone needs to be 20in tall and the ellipse has a max radius of 10in and a min radius of 8in.

So my question is how do i lay this out on a piece of paper so that i can form the cone after i cut it out.

Penny Nom lui répond.

A worm crawling home 2004-02-18

Cindy pose la question :
A worm is crawling to his home which is one meter away. The longer he crawls the weaker he gets and the less he can crawl the next day. If he crawls within 1/3000 of a meter of his home, he will find food. He must eat within twelve days. The first day he crawls 1/2 meter. The second day he crawls 1/4 meter. The third day he crawls 1/8 of meter. This pattern continues for twelve days. Make a Chart that shows the distance he has covered at the end of each day and the total he has covered at the end of each day. Does he make it to the Food in time?
Penny Nom lui répond.

Geometric sequences 2004-02-03

Alan pose la question :
hello, I am a junior in precalculus. we started working on geometric sequences today, it makes perfect sense on how it works. but why is it called that? if you could send me an answer to why geometric sequences have that name, I would be much appreciative.
Chris Fisher lui répond.

Intersecting a line and a curve 2004-01-29

Senthil pose la question :
between line and curve how can i find intersection point? could you write me the formula and explanation also sir.
Penny Nom lui répond.

Sets 2004-01-27

Susan pose la question :
My child has the following problems to solve, and we are puzzled. 1. Compare the subset symbols to the inequality symbols of less than or greater than.

2. If A, B & C are sets such that A has 47 elements, B has 32 elements, and C is a proper subset of B, what can you say about the number of elements in the following sets: A U B? A intersect B? B U C? and B intersect C?
Penny Nom lui répond.

A problem with sets 2004-01-20

Jason pose la question :
Given that the universal set S is the set of all sports fans, and
F={x|x is a football fan}
B={x|x is a basketball fan}
H={x|x is a hockey fan} a)Describe (F^B)' (f intersect b)' in words
b)Draw a Venn Diagram and shade the region that represents the set of football fans or both basketball and hockey fans.

Penny Nom lui répond.

The product of any n consecutive integers 2004-01-18

Fazia pose la question :
I have to prove that the product of any n consecutive integers is divisible by n!(eg:the product of five consecutive integers is divisible by 5!) It's easy enough to plug in numbers and prove it is true, but i'm finding it difficult to come up with a proper proof.
Claude Tardif lui répond.

Two consecutive negative integers 2004-01-17

Amanda pose la question :
Find two consecutive negative intergers whose product is 182.
Penny Nom lui répond.

37 with four 4'2 2004-01-03

Myra pose la question :
Using four fours and only four fours to get an answer of 37.
Claude Tardif lui répond.

Percent increase 2003-12-24

Frank pose la question :
How does one figure the percent of increase or decrease in the cost of an item?
Penny Nom lui répond.

An elliptical race track 2003-12-16

Judy pose la question :
the inner rail of a race track is a perfect ellipse. the track is a standard width all the way around. how can i prove that the outer rail is a ellipse?
Penny Nom lui répond.

Finding angles 2003-12-02

Jason pose la question :
I AM TRYING TO SOLVE A TRIG PROBLEM AND HAVE FORGOT HOW TO DO IT. WHAT I HAVE IS A RIGHT TRIANGLE WITH SIDE A BEING 14 FEET AND SIDE B BEING 3 FEET, USING PYTHAGOREAMS THEOREM SIDE C SHOULD EQUAL 14.318 FEET ON A RIGHT TRIANGLE BUT I AM TRYING TO REMEMBER HOW TO FIND MY ANGLES OTHER THAN THE ONE THAT IS 90 DEGREES.
Penny Nom lui répond.

A point and a line 2003-11-19

Meenakshi pose la question :
Given a line segment L(x₁,y₁) to (x₂,y₂) and a Point P(x₃,y₃).
I need the formula to find a point on the line L that is closest to the point (x₃,y₃).

Penny Nom lui répond.

The 4th difference 2003-11-17

Jack pose la question :
If i had a sequence which was the same at the 4th difference, aka difference to the 4th, like:

1 5 14 30 56 96 (sequence)
4 9 16 26 40
5 7 10 14
2 3 4
1 1

then what would be the set formulars to find out a, b, c, d, and e
as i know the equation has to be an⁴+bn³+cn²+dn+e
Penny Nom lui répond.

Divisibility by 7 2003-11-14

A student pose la question :
how do you test a number to see if it is divisible by 7 or not?
Penny Nom lui répond.

root24 = 2 root6 2003-11-13

Burke pose la question :
I know that all algerbra can be represented visually, for example: Y=9x+3 is a line on a two dimentional plane. Could Math Central please send me a visual representation of the proccess of simplifying square root like root24 equals 2root6
Penny Nom lui répond.

Chisenbop 2003-11-06

Jaclyn pose la question :
Hi there i was wondering if you would have any information on "counting on your fingers" or " Chisabop".
Penny Nom lui répond.

Knitting gauge and felting 2003-10-27

Sara pose la question :
I wish to create a pattern to knit an item that will then be felted, thus, shrink as a result. In order to determine the proper gauge to use in creating the item, I produced a gauge swatch, noted the original properties and then the post-felting properties. They are as follow:

Before Felting:
20 stitches(width) x 20 rows(height)yielded:
Gauge: 3.2 stitches(width) and 4 rows(height) = 1"
Dimensions: 6.25"(width) x 5.25"(height)

After Felting:
20 stitches(width) x 20 rows(height)
Dimensions: 4"(width) x 3"(height)

How do I calculate the percentage change in size to accurately determine the number of stitches and rows needed to produce the desired dimensions for the finished (felted) item?

Penny Nom lui répond.

Maine and Nevada 2003-10-24

Jimmy pose la question :
From 1989 to 1990, the population of Nevada increased b y 157,000, and that of Maine increased by 30,000. In 1990, the population of Nevada was 1,206,152, and that of Maine was 1,233,223. If the populations of the two states continue to increase at the same rates, when will the populations of Nevada and Maine be the same?
Write a verbal model for this problem
Write an equation for the model
Solve the equation and answer the question.

Penny Nom lui répond.

Arithmetic in bases other than 10 2003-10-22

Kim pose la question :
how do you add, subtract, multiply and devide in base 3, base 5, etc?
Penny Nom lui répond.

Squares in a rectangle 2003-10-21

Raj pose la question :
Draw a rectangle with sides of 3 and 4. Divide the sides into 3 and 4 equal parts respectively. Draw squares joining the points on the sides of the rectangle. You will have 12 small squares inside the 3 x 4 rectangle.

If you draw a diagonal of the rectangle, it will intersect 6 of the the 12 smaller squares.

Similarly, if you have a 4 x 10 rectangle, the diagonal would intersect 12 of the 40 squares inside the rectangle.

Is there an algebric equation that determines the number of squares that will be intersected by the diagonal of a rectangle?

Chris Fisher lui répond.

1 + 1 = 10 2003-09-17

David pose la question :
could you please explain to me how 1+1=10 thanks
Penny Nom lui répond.

The mean house price 2003-09-10

Carol pose la question :
Question:
I have to find the mean from the following example:

Price Range £000 No of Houses
55 and under 60 3
60 and under 65 6
65 and under 70 13
70 and under 80 21
80 and under 100 15
100 and under 130 7
130 upwards 1

I know when calculating the mean you use the mid points of the classes, but how does this work for the 130 upwards class? Also, does this still work given the difference in the classes (ie. 1st class is 5, 5th class is 20, etc). Any help to get me started would be greatly appreciated.

Penny Nom lui répond.

Converting from base 10 to base 5 2003-09-10

Susy pose la question :
My son, who is 9 in grade 5 has been asked to convert base 10 numerals into base 5.

His first question of:

24(10) he has calculated to be 4x5 + 4x1 = 44 (5)

The next question however is the tricky one.Ý We know the answer is supposed to be 100 but we find it difficult to get this in the way he understands it.

25 (10) = _________________ 100 (5)

Can you help us figure out how we reach the answer.

Claude Tardif and Penny Nom lui répond.

Consecutive integers 2003-09-07

Amy pose la question :
I was wondering if there was a proper way to write the solution to a problem requiring consecutive integers? Is it okay to write the solution as 5,4,3,2,1 or must it be written as 1,2,3,4,5?
Penny Nom lui répond.

Can 2 vertical planes intersect? 2003-09-06

Erin pose la question :
My question is can 2 vertical planes intersect?
Penny Nom lui répond.

One million seconds 2003-09-04

Vince pose la question :
If you can write a number each second for one million seconds, how many hours would it take?
Penny Nom lui répond.

Grooming the king's horses 2003-09-04

Janelle pose la question :
the stable boy had 90% of the kings horses groomed.the next day the king acquired 25% more horses. Now there was 105 horses not prepared for the kings men. How many horses did the king originally have?
Penny Nom lui répond.

Converting to base 10 2003-08-28

Karen pose la question :
My son is in 5th grade.Ý He is learning how to convert numbers from base 2 to base 10, and base 5 to base 10.Ý Can you explain it to me in the simplest terms?
Penny Nom lui répond.

Graphing a piecewise function 2003-08-24

Amber pose la question :
How do i begin to graph a piecewise function, absolute function or step function?
Penny Nom lui répond.

39 consecutive natural numbers 2003-08-19

A student pose la question :
Prove that among any 39 consecutive natural numbers it is always possible to find one whose sum of digits is divisible by 11.
Penny Nom lui répond.

Percentage decrease in sales 2003-07-31

Linda pose la question :
If I had sales in January of 2002 that were $42,493.73 and sales that were $37,281.59.Ý The difference is $5374.50.Ý What is the percentage of decrease in sales?
Penny Nom lui répond.

Is 3/5 CLOSEST to 0, 1/2 or 1? 2003-07-09

A student pose la question :
I would like to know is 3/5 CLOSEST to 0, 1/2 or 1. And can 3/10 go either way as to be closest to 0 or 1/2.
Penny Nom lui répond.

Setting up a word problem 2003-06-30

Christie pose la question :
A rectangular corral is forty feet longer than it is wide. If the perimeter is 220 feet, determine the length and width of the corral.
Penny Nom lui répond.

Sesame Street on Stage 2003-06-25

Christie pose la question :
Sesame Street on Stage has different ticket prices for adults and for children under 6. Beth and her two children, ages 3 and 4, paid $15 to gain entrance, while Jamie and John Jacobs and their 2-year old daughter got in for $19.50. What is the ticket price for adults?
Penny Nom lui répond.

A 40% markup 2003-06-12

Nick pose la question :
I am attempting to determine the Retail price of an item that costs me 11.00. Our company wants to sell it at a markup of 40%. I calculated this two ways, first the way I thought it should be done. Second, the way the calculator does it (and my accountant).

Cost + Cost*(percentmarkup/100)= retail price 11.00 + 11.00*.40 = retail price 11.00 + 4.40 = 15.40 retail price

Using the calculators Mark Up key the answer is 18.33. Or 7.33 more than the cost or 67%.

I am confused by this Mark Up key and how it calculates. I used a cost of $10.00 and marked it up 50%. I thought it should equal $15.00 but the calculator says $20.00? This seems to be 100% markup, yes?
Can you explain the difference between the way I did it and the way a Business calculator does it?

Penny Nom lui répond.

A project about crosses 2003-06-10

Joel pose la question :
I have this project to do about crosses and I can't think of what the answer is for the following questions: What is the area rule of the crosses (the table below will help you)?
Cross Number Area sq cm

1 5

2 13

3 25

4 41

5 61

I also need to know what the formula is for it?

Penny Nom lui répond.

Teaching second grade 2003-06-10

A teacher pose la question :
I am going to be teaching second grade next year. How can I differentiate instruction in mathematics to meet the needs of all of my students, from those who need intervention to those who need challenges? What are some techniques I can try for this grade level?
Diane Hanson lui répond.

$1/week for week 1 and then double each week 2003-05-28

A student pose la question :
I AM DOING A PROJECT FOR MATH I AM TRYING TO CREATE A SEQUENCE BASED ON: MAKING A SALARY OF $1/WK FOR THE FIRST WEEK WITH IT DOUBLING EVERY WEEK FOR 52 WEEKS, SO MY SEQUENCE LOOKS LIKE THIS: 1,2,4,8,16,32,64,128,256,512,1024 ETC. THERE WOULD BE 52#'s TOTAL IN MY SEQUENCE.I BELIEVE IT IS CALLED A FINITE SEQUENCE. MY QUESTION IS HOW DO I CREATE A FORMULA/RULE FOR THIS PARTICULAR SEQUENCE? MY GOAL BEING TO FIND THE 52nd TERM IN THE SEQUENCE.
Penny Nom lui répond.

Two sequences that agree in the first 4 terms 2003-05-26

A student pose la question :
Is it possible to have two formulas that define sequences that agree on the first four terms but not the rest?
Penny Nom lui répond.

The cross-section of a football field 2003-05-25

Francis pose la question :
Have you ever walked on a football field covered with artificial turf? If so, you probably noticed that the field is not flat. The profile of the surface is arched and highest in the centre, permitting rainwater to drain away quickly.
height from base to highest point- 45.75 centimetres distance of the field- 50 metres
a) The diagram shows the profile of an actual field, viewed from the end of the field. Assuming that the cross-section is a parabola, find the algebraic model that describes this shape.
b) Use your equation to determine the distance from the sidelines where the field surface is 20 cm above the base line.

Harley Weston lui répond.

A trig identity 2003-05-20

Patty pose la question :
Please help with the following

1/ tanx + cotx = sinxcosx
Penny Nom lui répond.

R= 5.3lnx + x. 2003-05-11

A student pose la question :
Reaction R to a dose x is given by: R= 5.3lnx + x. For a certain drug, R must not exceed 21. Show that a dose between 8 and 12 units satisfies this requirement & find, correct to 5 decimal places, the greates value of x which satisfies this condition?
Harley Weston lui répond.

positive multiples of 10 that are the sum of four consecutive integers 2003-05-01

Taurus pose la question :
How many positive multiples of 10 that are less than 1000 are the sum of four consecutive integers?
Penny Nom lui répond.

Profit for a dance studio 2003-04-28

Craig pose la question :
A dance studio charges $80 per student for a series of 2 hour lessons. The studio's costs are $30 per hour for the instructor, $15 per lesson for the room rental, and $3 per student for miscellaneous expenses. If x is the number of students enrolled in the class, express the studio's profit P(x) in terms of x. Find the profit if 10 students are enrolled in the class.
Penny Nom lui répond.

The product of four consecutive integers is 3024. 2003-04-25

pillar pose la question :
The product of four consecutive integers is 3024. What are those numbers.
Penny Nom lui répond.

One one 2003-04-22

Brad pose la question :
find the next two rows of numbers?
1 1 1 2 1 1 1 1 2 3 1 1 2 1 1 1 2 1 3

Leeanne Boehm lui répond.

Chopping trees 2003-04-19

Tamara pose la question :
The master needs some of the trees (twenty, to be exact) at the back of his spooky old mansion cleared to make way for a new evil laboratory, so he decides to send some his slaves to do the work for him.
He initially sends out four of his men, armed with axes, to chop the trees down. Due to the fact he is very impatient, every ten minutes he sends out another man to help with the work.
Assuming that it takes one man 30 minutes to chop down 1/3 of a tree, how long till all twenty trees are chopped down?

Penny Nom lui répond.

How many hits? 2003-04-06

Jack pose la question :
My name is Jack. I'm a uncle. Student is in the 5th grade email is above.

If a baseball player at sping training had a good season with the following:

one seventh of his hits were doubles.
12.5% of his hits were home runs.
But didn't have any triples.
How many hits did he have?

Can you give me an explanation of you solved the problem.

Penny Nom lui répond.

Uses of conic sections 2003-04-01

William pose la question :
My name is William and I am doing a research paper on conic sections for my 12th grade math class. Part of the project is to find two conic sections in our world today and explain what there purpose is. I really need help in this area because I've been searching the internet for where conic sections are used in our world today and I really can't find anything. If you can tell me specific building or a pyramid that contains conic sections that would be great. Or even something in the universe would be helpful.
Leeanne Boehm lui répond.

Friends and enemies 2003-03-24

Becky pose la question :
Consider a room that contains six people. Any two people are either friends of each other, or they are enemies.

A. Argue why there are three people, all who are friends, or there are at least three people, all who are enemies

B. Rephrase the situation using graph terminology, using all of these terms correctly: vertex, edge, graph, complement, clique, independent set, and bipartite.

Penny Nom lui répond.

A sequence that converges to e 2003-03-16

Dane pose la question :
Something I noticed fooling around with a calculator about 30 years ago.
Considering e = 2.718281828459045....
Using Window's Calculator you will find

1.1¹¹ = 2.8531167...
1.01¹⁰¹ = 2.731861...
1.001¹⁰⁰¹ = 2.71964085...
1.0001¹⁰⁰⁰¹ = 2.71841774...
1.00001¹⁰⁰⁰⁰¹ = 2.7182954...
1.000001^10000011 = 2.178231875...
1.0000001^10000001 = 2.178219643...

There apears to be a pattern. My conjecture is:

1.'infinite number of zeros'1^{1'infinite number of zeros'1} = e.

Penny Nom lui répond.

A section of land 2003-02-25

Bev pose la question :
How many acres in a section of land? How many square miles is in a secion of land?
Penny Nom lui répond.

Percentage decrease 2003-02-20

Hope pose la question :
What number decreased by 33¹/₃% is 30?
Penny Nom lui répond.

Numbers in base 5 2003-02-16

Lori pose la question :
I'm trying to help my 6th grader with converting numbers like 82 to base 5 and 182 to base 12. We saw your examples on 613, but still are confused.
Penny Nom lui répond.

Finite differences 2003-02-10

Jenny pose la question :
I need to find a formula that will work with any number.
I am finding the volume of a 3d cross- shape. Here are my results so far:

Term Number 0 1 2 3 4 5 nth term 1 7 25 63 129 231 1rst diff 6 18 38 66 102 2nd diff 12 20 28 36 3rd diff 8 8 8

I can't seem to find a formula that will work with any number. Any help would be much appreciated.

Penny Nom lui répond.

Three consecutive positive intergers 2003-02-09

Yew pose la question :
Prove that when we multiply any consecutive positive intergers, the result is always divisible by 6.

ex. (7)(8)(9) = 504 = 6 (84)
Penny Nom lui répond.

The sum of the first 1000 even integers 2003-02-06

Jill pose la question :
What is the sum of the first 1000 even integers?
Paul Betts lui répond.

Arithmitic sequence 2003-02-01

A student pose la question :
I am having problems solving this arithmetic sequence... 1, 5, 10, ___, 50, 1.00, ___, 10.00, ... I believe the answers to be 25 and 5.00 but I can't figure why.
Claude Tardif lui répond.

1+2+3+...+500 2003-01-31

Brian pose la question :
What is the sum of the numbers from 1 to 500 inclusive?
Paul Betts lui répond.

25% more 2003-01-16

Charlie pose la question :
If I buy something for $10 and want to sell for 25% more, do I multiply by 1.25 or divide by .75? Or another way - why do I get $13.33 when dividing by .75 ?
Penny Nom lui répond.

Collinear Points 2003-01-13

Gary pose la question :
Which of the 4 points are collinear when you construct the following concurrent lines or rays of a triangle?

P(1), the point where the angle bisectors intersect.

P(2), the point where the altitudes (or extensions) intersect (inside or outside of the triangle).

P(3), the point where the medians intersect.

P(4), the point where the perpendicular bisectors (or extensions) of the three sides of a triangle intersect.

This is for my 9-12 high school class in geometry.
My name is Gary

Thanks for your help.
Gary

Harley Weston and Chris Fisher lui répond.

What is larger than infinity? 2003-01-12

Dana pose la question :
What is larger than infinity?
Claude Tardif and Harley Weston lui répond.

A rectangular prism 2003-01-09

Julie pose la question :
How many faces on a rectangular prism and how many bases? Can the base also be a face and can a face also be a base?
Diane Hanson lui répond.

Repeating decimals 2003-01-08

A student pose la question :
If k=.9repeating, and 10k=9.9repeating then 10k-k=9k, k=1 therefore .9repeating=1 and 1/3=.3repeating 3x1/3=.3repeatingx3, 3/3=.9repeating, therefore 1=.9repeating
It would seem to me that .9repeating approaches one but never quite makes it. Can you clarify?

Penny Nom lui répond.

Constructions of polygons 2003-01-03

Garrett pose la question :
Our teacher just finished the constructions unit, and he mentioned briefly about odd sided figures such as pentagons and septagons, only that they're very hard. My question is, how do you draw, with a compass and a straight edge, a pentagon and septagon?
Chris Fisher lui répond.

The intersection of conics 2002-12-19

Glenda pose la question :
We are studying systems of equations where two conic sections are the two equations that we are solving simultaneously. We were studying the number of solutions that are possible if you have an ellipse and a parabola. We all agree that there can be none, one, two, three or four solutions. The question that the students had for me was whether or not a portion of an ellipse and a parabola can overlap and thereby allow an infinite number of solutions. What should I tell them?
Chris Fisher and Harley Weston lui répond.

A bouncing ball 2002-12-14

Eman pose la question :
Q : When a childís ball is dropped from a height h metres on to a hard, flat floor, it rebounds to a height of 3/5h metres. The ball is dropped initially from a height of 1.2m.

Find the maximum height to which the ball rises after two bounces.

Find the total distance that the ball has traveled when it hits the floor for the tenth time.

Assuming that the ball continues to bounce in the same way indefinitely, find the total distance that the ball travels.

Penny Nom lui répond.

A geometric sequence 2002-12-02

Wanda pose la question :
the fifth term of a geometric sequence is 5/16. the common ratio is 1/2. What are the first four terms of the sequence.
Penny Nom lui répond.

Combinations of 1,2,3,...,10 2002-11-27

Gord pose la question :
If I had the numbers from 1-10 how many different combinations would i have.....would it be 100....since that is 10 squared.
Penny Nom lui répond.

Making 7 2002-11-26

Bill pose la question :
At one time I had the answer to this math equation but I have lost it and can't seem to regain it. I may be going at it wrong but as I recall there were the numbers 1 through 4, and the std operators, +, -, /, *, and parentheses. The object was to make the four numbers with the operators equal to 7. Each number and operator may be used only once. My 9 year old loves these quizzes but I can't give it to her if I can't provide the correct answer.
Claude Tardif lui répond.

A two stage rocket 2002-11-26

Hoda pose la question :
a two stage rocket accelerates in free space by ejecting fuel at a constant relative speed , v(ex). the full fuel load makes up 80% of the initial mass of the entire two stage rocket . the rocket accelerates from rest until at the end of the first stage when 75% of its fuel has been burnt. find an expression for the speed of the rocket at the end of the first stage in terms of v(ex).
Claude Tardif lui répond.

Differentiating inverses 2002-11-20

Amy pose la question :
f(x)= x³+x+1, a=1 find g'(a) (g = f^-1). I am having trouble finding g(a).
Penny Nom lui répond.

The horse race 2002-11-19

Pat pose la question :
The Horse Race Three horses run a race. In how many different ways can the three horses finish the race if ties are allowed?
Penny Nom lui répond.

The volume of water in a hose 2002-11-13

David pose la question :
I trying to find out how much water 500 ft of 3/4 inch hose will hold. I'd also like to know how you figured the answer.
Penny Nom lui répond.

Chisanbop 2002-11-07

Paul pose la question :
I'm trying to find the book/books that explain this system? I have one small book that explains the very beginning of the system, but covers only about 10 to 20%. I'v tried several book sellers and have had no luck.
Diane Hanson lui répond.

What is nth term? 2002-11-06

Joga pose la question :
What is nth term:
First sequence:
2, 4,7,11, 16, nth term

Second sequence:
4,10, 28, 82, nth term

Penny Nom lui répond.

A house's selling price 2002-11-05

Tanisha pose la question :
a CERTAIN REAL-ESTATE AGENT RECEIVES $6 FOR EVERY $100 OF A HOUSE'S SELLING PRICE. HOW MUCH WAS A HOUSE SOLD FOR IF THE AGENT $10,725._
Penny Nom lui répond.

Compass points 2002-11-05

Mhairi pose la question :
I was asked this in maths but I am not sure if it is geography. Name all the compass points? We have been given 8 but he told us there is more and we have to name them.
Chris Fisher lui répond.

The percentage grade of that hill 2002-11-05

Cathy pose la question :
If there is an 80ft climb over a kilometer(about 3280ft) what is the percentage grade of that hill?
Penny Nom lui répond.

Jimmy's hits 2002-10-27

Patty pose la question :
One seventh of Jimmy's hits were doubles
12.5% of his hits were homeruns
Jimmy had 82 singles
He did not have any triples

How many hits did Jimmy have? (Be sure to include the equation that represents the number of hits)
Penny Nom lui répond.

x⁴ + x⁵ = 100 2002-10-27

Bill pose la question :
One of my students has stumped me. He asked how to solve the equation 4^x + 5^x = 100
All I can think of are graphing methods to get an approximate solution. What am I missing?

Harley Weston lui répond.

Two problems 2002-10-14

Eva pose la question :
a) How many different equivalence relations can be defined on the set X={a,b,c,d}?

b)Show that 6 divides the product of any 3 consecutive integers. I know it is true that 6 divides the product of any 3 consecutive integers. However, i have problem showing the proof.

Leeanne Boehm and Penny Nom lui répond.

Tree diagrams 2002-10-12

Denean pose la question :

For lunch, students can choose juice or milk; hamburger or pizza; and a banana or apple. How many lunch combinations can the students make?

In an experiment, Monty can use paper towels or cloth. He can choose red, green, or yellow food coloring. How many combinations are there?

Penny Nom lui répond.

Nixon, Jefferson, and Madison 2002-10-08

Lisa pose la question :
The longest-lived US presidents are John Adams(age90), Herbert Hoover (also90), and Harry Truman (88). Behind them are James Madison, Thomas Jefferson, and Richard Nixon. The lattter three men lived a total of 249 years, and their ages at the time of death form consecutive odd integers. For how long did Nixon, Jefferson, and Madison live?
Penny Nom lui répond.

Baseball, basketball and football 2002-10-08

Debbie pose la question :
The school newspaper is interviewing 6th grade students to see what sports they follow regularly on TV. Of the 70 students interviewed; 40 enjoyed basketball; 40 enjoyed baseball; 40 enjoyed football; 20 enjoyed basketball and football; 22 enjoyed baseball and basketball; 27 enjoyed football and baseball; and 12 enjoyed all three sports. How many students out of the 70 interviewed didn't follow any one of the three sports?
Leeanne Boehm, Penny Nom and Walter Whiteley lui répond.

Sums of evens 2002-09-14

Rosa pose la question :
How do I find a geometric way to easily compute sums of consecutive even numbers 2 + 4 + 6 + ....
Leeanne Boehm and Harley Weston lui répond.

Base 5 numbers 2002-09-13

Vera pose la question :
? how do you change a base 10 number to base 5
Penny Nom lui répond.

7+8+9+...+1000 2002-09-11

Shirley pose la question :
My question is what is the formula for adding up numbers when you don't start with number 1? For example 3 + 4 + 5 + 6 = 18. But how could you arrive at the answer without adding all the numbers?
Penny Nom lui répond.

How do start from 2700 and get 35% back out? 2002-09-09

Dennis pose la question :
2000 x 0.35 = 700 + 2000 = 2700
How do start from 2700 and get 35% back out? If I have 2700, how do I figure out that 35% of 2000 is 700 and adding the two them together will get me 2700?
Penny Nom lui répond.

Social security numbers 2002-09-06

Chris pose la question :
How many different number combinations are there for the social security system? We know that there are only a certain ammount of combinations available and the current US population is at 281 million. The number system should include as many nine digit combinations as possible using the numbers 0-9 in multiple different spots.
Penny Nom lui répond.

8,27,64 . . . 2002-09-05

Mike pose la question :
We have been trying with no luck all night to complete the following math pattern (next 3 entries) 8,27,64 . . . Any ideas??
Penny Nom lui répond.

1, 2, 4, 8, 16, 32, etc. 2002-09-04

Ginger pose la question :
I've been working with finding the nth term for a few weeks, and i can't seem to figure this one out!
1, 2, 4, 8, 16, 32, etc.

Leeanne Boehm lui répond.

Express 5120 as a sum of consecutive numbers 2002-08-25

Todd pose la question :
Express 5120 as a sum of more than 1 consecutive number.
Leeanne Boehm lui répond.

Sets and elements 2002-08-22

Dianne pose la question :
I want to know why its okay to say that, for example, 6 is an element of the set of integers, but you get counted off for saying that the set of 6 is an element of the set of integers. How come?
Judi McDonald lui répond.

A paper model of a cone 2002-08-14

Bruce pose la question :
I have made a paper model of a cone, cut a sloping section, and removed the top. I have drawn the major and minor axis on the paper surface of the section. The major axis is not symmetrical about the minor axis. To me, this is not an ellipse. To me, an ellipse is a tubular section, because this gives a symmetrical major axis. What is your opinion?
Walter Whiteley and Chris Fisher lui répond.

Percentage 2002-07-20

Sally pose la question :
If 20% of 100 is 80, then why is the percentage difference between 80 and 100 25%.
Penny Nom lui répond.

A polygon inscribed within an ellipse - Part 2 2002-07-08

Steven pose la question :
I recently sought your advice about a problem that I have been working on for eight years or so concerning a polygon inscribed within an ellipse. I think that I may have confused matters by the way in which I put the question and hope that the enclosed diagram will clear matters up. In the ellipse below I have drawn three chords inscribed within one quadrant ( this would pertain to a twelve sided figure within the whole ellipse). These chords are exactly the same length as each other, for example if the major axis of the ellipse was 360 and the minor axis 240 I have worked out that a twelve sided figure would have sides of 78.2487. However I worked this out empirically with a method that could only be described as gruelling I would be most grateful if you could tell me of a method that would work for any ellipse and any number of sides.
Chris Fisher lui répond.

An equalateral polygon inscribed within an ellipse 2002-06-30

Steven pose la question :
How would you calculate the length of one of the sides of an equalateral polygon (of n sides) inscribed within an ellipse ( of any eccentricity ) where all of the vertices exactly touch the perimeter of the ellipse?
I know that when the eccentricity is zero ( i.e a circle ) the formula: r * (sin(180/n) * 2) will suffice. But what about when the eccentricity is greater than zero?

Chris Fisher lui répond.

What is the next term? 2002-06-21

A student pose la question :
What is the next term in the sequence:
1, 5, 14, 30.....

Penny Nom lui répond.

| n + 4 | + | 3 - 2n | = 16 2002-05-24

Randall pose la question :
I don't seem to be able to solve this: | n + 4 | + | 3 - 2n | = 16
Penny Nom lui répond.

Sequences that agree on their first four terms 2002-05-16

Mike pose la question :
Are there two formulas that define sequences that agree on their first four terms, but differ on the fifth term and all succeeding terms?
Chris Fisher lui répond.

The law of cosines and obtuse angles 2002-05-09

Bryant pose la question :
The question that I am pondering is that I need to derive the law of cosines for a case in which angle C is an obtuse angle.
Penny Nom lui répond.

What's the next term? 2002-04-29

A student pose la question :
Find the nth term for the following:
1) 12, 30, 56, 90, 132
2) 6, 30, 84, 180, 330
3) 8, 15, 24, 35, 48
4) 10, 17, 26, 37, 50
5) 24, 40, 60, 84, 112
6) 24, 60, 120, 336, 504

Please show the FULL working out.

Penny Nom lui répond.

Conversion of units 2002-04-29

Matt pose la question :
I am having trouble finding a workable equation for the following problem, particularly the conversion of two systems of measurement.
The question states that there are 27 grams of salt in a kilogram of seawater. And it asks how many tonnes (1 tonne = 1000 kilograms) of salt are there in one cubic kilometer of ocean. It also says that the density of seawater is 1.1 g/cm3.

What is the equation and how do I figure out how many kilograms there are in a cubic kilometre?

Harley Weston lui répond.

Ratios 2002-04-17

A student pose la question :

Medication is givin at 1cc. per 20 pounds of body weight. A dog weighs 16 pounds how many ccs. of medication does the dog get?

Dr. Lee wants you to prepare 1000 ml. of a 10% dextrose solution in lactaed ringers for diuresis or a patient you have a 1 L bag of lactated ringers and 500 ml of 50% dextrose for injection. How would you prpare the solution?

Penny Nom lui répond.

Diagonals in a polygon 2002-04-10

Murray pose la question :
If you have a regular polygon with n sides and you draw all (n-3)n/2 diagonals how many intersection will they form with each other and how many sections will they devide the polygon into.
Caude Tardif and Chris Fisher lui répond.

Composition of functions 2002-04-06

Yvonne pose la question :
In our new text book, the following question occurs: State the domain and range of g(f(x))given that f(x) = -x² - 4 and g(x) = sqrt(x)
The range of f(x), x<=-4, is the domain of g(x). BUT, there is no solution in the Real numbers for g(f(x))= sqrt(-x² - 4).

In the solutions it says that this is not a function and therefore does not have a domain or range. Is it a relation? Is it anything?

Claude Tardif lui répond.

If you conect all the vertices of a regular n-gon... 2002-04-01

Murray pose la question :
If you conect all the vertices of a regular n-gon with lines you will have (n-3)(n/2) lines inside the polygon. I want to find out how many sections these lines divide the polygon into and how many intersections they have with each other.
Claude Tardif lui répond.

Some 5 card hands 2002-03-28

A student pose la question :
From a standard deck of cards how many 5 card hands are possible consisting of a. exactly 4 hearts

b. two cards of one kind and three of another(like a full house).
Penny Nom lui répond.

A cone in 3 space 2002-03-20

Matthew pose la question :
Let C in R³ be the cone defined by x² + y² - z² = 0
(A) Let P be the plane described by x + 2z = 1

(i) Find a description of P in terms of two parameters s and t
.
.
.
Walter Whiteley lui répond.

Percentage difference 2002-03-08

Tedd pose la question :
Can you give me the formulas for calculating percentage differences between two numbers? For example: if the first number is 10 and the second number is 15, then the second number is 50% larger than the first number. However, the formula to calculate that percentage won't work if the first number is greater than the second number as in the following example: The first number is 15 and the second number is 10, with the second number being 33.3% less than the first number. Or maybe I'm mistaken and the same formula will work in both situations.
Penny Nom lui répond.

A sequence 2002-03-07

Caroline pose la question :
hi, here is the problem,

1
11
21
1211
111221
_ _ 2_ _ _
we can't get the sequence of the last line ,with the 3rd number being 2,thanks

Walter Whiteley lui répond.

1,4,27,____,_____46656 2002-02-21

Brenda pose la question :
1,4,27,____,_____46656..... please find the fourth and fifth numbers in this sequence.
Penny Nom lui répond.

Alfredos house number 2002-02-21

Aunt Patty pose la question :
Alfredos house number is between 20 and 35. The sum of the digits is less than 5. If you subtract 1 from it you would get a multiple of 3. If you add three, you get a multiple of 5. What is Alfredos house number.
Penny Nom lui répond.

The perimeter of an ellipse 2002-02-14

Harry pose la question :
I am planning to build a coffe table with an ellipse of 24x36 for the top. I wish to decorate the edge and need to know the lenght of the perimeter for lay out purposes. Is there an easy way to approximate this figure with out using intergal calculus?
Penny Nom lui répond.

Parabolas 2002-02-03

Kuang pose la question :
-Who is credited for working with or studying the Parabola?
-What is a conic section?

-What does a parabola look like?

-How is a parabola formed?

-Where and how are parabolas used today in the real world?

Harley Weston lui répond.

Baseball and sit ups 2002-01-31

A student pose la question :
A baseball team won 8 more games than it lost. If it played 56 games, how many games did it win?
On the first day of practice, Paul did 3 sit ups. On the second day he did 5, and on the the third day he did 8, and on the fourth day he did 12. If this pattern continued, how many sit-ups did ihe do on the sixth day of practice?

Penny Nom lui répond.

The size of a lot 2002-01-26

Claudia pose la question :
I own a piece of property that I need to know the square feet for assessment purposes. The figure they came up with is wrong. They measured from one point to another and halved the sums but that means I own the cul de sac and we don't. My lot is 55 feet wide and one side is 108.96 feet and the other side is 146.04 that extends all the way to a circle. The front of the lot on the cul de sac is stated on the survey like this. 78.21 feet where R=40 feet. This large arc is taken off the size of our land. How many square feet is our lot.
Harley Weston lui répond.

Successive differences 2002-01-20

Linsey pose la question :
what is the rule for working out the formula for a sequence with three lines of difference? eg.
1, 3, 7, 15, 29 1st line differences: 2, 4, 8, 14 2nd line differences: 2, 4, 6 3rd line differences: 2, 2

Penny Nom lui répond.

Rolling 5 sevens before rolling a six or an eight 2002-01-20

Tony pose la question :
When rolling 2 dice, what is the probability of rolling 5 sevens before rolling a six or an eight?
Andrei Volodin and Penny Nom lui répond.

My salary is doubled everyday for 30 days 2002-01-17

Kanishk pose la question :
I recieve 1 penny the 1st day, 2 pennies the 2nd day, and my salary is doubled everyday for 30 days. How much money will I have by the end of the 30 day time period? (Is there a way of solving this problem without a chart?)
Penny Nom lui répond.

A sequence 2002-01-16

Chris pose la question :
I have spent two days trying to determine the pattern to the following set of numbers: 1,4,9,1,6,2,5,3,6,4,9,6,4,8,1,____. I need the next four numbers to the sequence.
Claude Tardif lui répond.

Children and probability 2002-01-16

Bill pose la question :
If a family has four children, what is the probability that all 4 are the same sex?
Vanrei Volodin lui répond.

Papy's Computer 2002-01-11

Mary-Anne pose la question :
My second-grade son brought home a fun math worksheet which involved calculating sums using "Papy's Computer." I had never heard of this before and found it to be quite interesting. Each digit in a decimal number is represented by a 2x2 grid. Each grid square corresponds to one of the numbers 1,2,4, or 8.
Harley Weston lui répond.

A sequence of number pairs 2002-01-10

Terry pose la question :
Three is the first number of a pair, and 8 is the second.

a. If 50 is the first number, what is the second number?
b. If 200 is the first number, what is the second number?
c. If 89 is the second number, what is the first number?
d. If a number n is the first number, what is the second number?

3-8
4-11
5-14
6-17
____
____
____
10-29
____
____
____

Peny Nom lui répond.

450 students 2001-12-19

Jessie pose la question :
My teacher told me that the number of ways of lining up the 450 students in our school is larger than the number of atoms in the universe. Is this right?
This question came to Good Question, a regular feature on the CBC Morning Edition radio show in Saskatchewan.

Denis Hanson and Harley Weston lui répond.

A 7% increase 2001-12-12

Lorraine pose la question :
how do you calculate an old salary if the only information you have is current salary and the percentage increase received. For example if I make $15.86 an hour and I received a 7% increase, how much did I used to make?
Penny Nom lui répond.

Can a infinite set be smaller than another infinite set? 2001-11-29

Carlos pose la question :
Can a infinite set be smaller than another infinite set? If so why?
Chris Fisher and Penny Nom lui répond.

3, 6, 10, 15, 21 2001-11-29

Patrick pose la question :
we are trying to find the expression to solve for the nth term in the pattern
3, 6, 10, 15, 21

Denis Hanson lui répond.

A lighthouse and related rates 2001-11-29

Melissa pose la question :
A lighthouse is located on a small island 3 km away from the nearest point P on a straight shoreline, and its light makes 4 revolutions per minute. How fast is the beam of light moving along the shoreline when it is 1 km from P?
Penny Nom lui répond.

Undetermined coefficients 2001-11-22

Hoda pose la question :
The equation is:
y" - 2y' + y = t e^t + 4

We need to use The method of Undetermined coefficients. I have tried assuming that the solution is Ate^t+Be^t+C, but all I get is C=4 and I tried (At²+Bt+C)e^t+D, but again I get 0=0 when I calculate the first and second derivatives, so i get no information on the constants. Any suggestions?

Harley Weston lui répond.

Matrix 2001-11-21

Hoda pose la question :
I have a question about matrix multiplication; well, actually, matrix division. I am assuming that matrices are divided the same as they are multiplied; that is, row by column. But what happens if you have to divide by zero? How does this affect the resulting matrix?
Patrick Maidorn and Penny Nom lui répond.

Cardinality of sets 2001-11-19

Tania pose la question :

Show that the cardinality of P(X) (the power set of X) is equal to the cardinality of the set of all functions from X into {0,1}.

Show that (the cardinality of the natural numbers set) |N| = |NxNxN|.

Show that the cardinality of the set of prime numbers is the same as the cardinality of N+

Walter Whiteley lui répond.

Number sequences 2001-11-17

Stephanie pose la question :
My name is Stephanie. My grade 7 math class is studying number sequences and, to me, they make almost no sense at all. Here I wrote down 2 of the many problems I have for homework and was wondering if you could explain them to me (I have to find the next 3 numbers in each sequence.) It would be a big help!
10, 14, 18, 22, _, _, _.

12, 21, 39, 75, _, _, _.

Penny Nom lui répond.

Subsets of a countably infinite set 2001-11-14

Tania pose la question :
How could I show (and explain to my son) that any countably infinite set has uncontably many infinite subsets of which any two have only a finite number of elements in common?
Claude Tardif lui répond.

Inequalities 2001-11-13

Pat pose la question :
When writing the solution to an inequality, why is the solution written in set notation? {x/ }
Penny Nom lui répond.

2=the square root of (2 + the square root of (2 + the square root of (2 +...))) 2001-11-05

Cynthia pose la question :
justify algebreically, that:
2=the square root of 2 + the square root of 2 + the square root of 2 + the square root of 2 + the square root of 2 + and so on, .......

Penny Nom lui répond.

Applied geometry 2001-11-02

Jenny pose la question :
Where can I find some hands-on activities for my Applied Geometry classes? I want to do more activities with them that allow us to get out of the classroom. However, I want to use activities that use only inexpensive equipment because I usually buy the equipment myself.
Walter Whiteley lui répond.

A lighthouse problem 2001-11-02

A student pose la question :
A lighthouse at apoint P is 3 miles offshore from the nearest point O of a straight beach. A store is located 5 miles down the beach from O. The lighthouse keeper can row at 4 mph and walk at 3.25 mph.

a)How far doen the beach from O should the lighthouse keeper land in order to minimize the time from the lighthouse to the store?

b)What is the minimum rowing speed the makes it faster to row all the way?
Harley Weston lui répond.

Why do you flip the inequality sign? 2001-10-26

Sean pose la question :
I have a question about an inequality problem. Here it is: Solve and graph 5 - 3x => 17. (=> is greater than or equal). Please tell me why you flip the inequality sign when divinding by a negative number.
Penny Nom lui répond.

A geometric series 2001-10-24

Tashalee pose la question :
The sum of the first 3 terms of a geometric series is 13. The sum of their reciprocal is 13/9. how do you find the first three terms?
Penny Nom lui répond.

Why quadratic for a second degree equation? 2001-10-20

Jana pose la question :
Why do we use the word quadratic to describe second degree equations?
Penny Nom lui répond.

60 seconds in a minute 2001-10-11

Andy pose la question :
I am a fourth grade teacher. Yesterday my students asked "Why are there 60 seconds in a minute?" Which also led to 60 minutes in an hour? I have had trouble determining why the number 60? Any help would be appreciated.
Penny Nom lui répond.

Ratio and proportion 2001-10-10

Steve pose la question :
Where would you use a proportion and/or a ratio in a real life job or problem.
Leeanne Boehm and Walter Whiteley lui répond.

Who owns what pet? 2001-10-03

A parent pose la question :
Don, Frank, Jenny, and Ken each come from one state, either Alaska, Maine, Montana, or Oklahoma. They each speak one primary language, either English, french, Russian, or Spanish. And they each have one of four pets, a chinchilla, a dog, a hamster, or a turtle.
Figure out which language and what pet each of the four people have, using the following clues.
.
.
.

Judi McDonald lui répond.

1+2+3+...+1000 2001-10-01

Louise pose la question :
Find a quick way to add all Intergers (whole Numbers) between 1 and 1000?
Walter Whiteley lui répond.

Find the pattern 2001-09-26

A parent pose la question :
MY SON HAD ON A WORKSHEET WHAT I HAVE LISTED BELOW, BUT WE CAN'T SEEM TO FIND THE PATTERN. MOST THE TIME WE CAN, BUT THIS ONE IS DIFFERENT.
6,___, 9,____,____,_____,_____,_____

Caude Tardif lui répond.

Four sequences 2001-09-24

Nicole pose la question :
I have a few questions I couldn't figure it out. So any help will be great to find the next three numbers or letters. Here's the patters...

DEGHNORY, EHILMU, HIILMTU, BEILLMRUY,...

50, 33, 25, 20, 16, 14, 12,...

1777, 1795, 1818, 1819, 1820, 1822, 1836, 1837..

A,H,I,M,O,T,...

Chris Fisher and Penny Nom lui répond.

An egg shaped island 2001-09-22

Karen pose la question :
I am a civil engineering designer trying to design an egg shaped island. I want a 30' radius at the top and a 40' radius at the bottom and the longest length of the egg to be 125'. Is there standard geometry for an egg shape? I am not held to exact radii or the length given.
Chris Fisher lui répond.

Counterclockwise 2001-09-14

Rolanda pose la question :
When Descartes invented the coordinate system he decided to number them counter-clockwise. Why?
Chris Fisher lui répond.

Arithmetic sequences 2001-09-10

Rachel pose la question :
I can't seem to figure out a problem that deals with arithmetic sequencing. This is the question: The 5th term in an arithmetic sequence is 1/2, and the 20th term is 7/8. Find the first three terms of the sequence. I attempted this problem with the formula: An = a + (n-1)d (where the n represents the nth term, a is the first term, and d represents the common difference) I keep getting -9.5 for the first number, and then 3/120 as the common difference between the numbers. But as I have figured it, the sequence is getting greater and greater, and my data does not go with the terms given.
Penny Nom lui répond.

The best of 7 2001-09-08

Michelle pose la question :
Professional basketball, hockey, and baseball championships are decided on the best 4 out of 7 games. The first team to win four games wins the championship. In how many possible ways could the team win the championship series after winning the first game?

Example: Game 1 2 3 4 5 6 7 Result W L L W W W

Leeanne Boehm lui répond.

Bisecting angles 2001-08-27

Monica pose la question :
Ray QS is the bisector for angle PQR. Find the measure of angle PQS and PQR if the measure of angle SQR is 52 degrees.
Penny Nom lui répond.

A sequence 2001-08-25

Sharon pose la question :
1
11
21
1211
111221
312211
1311221
1113213211
31131211131221
13211311123113112211
What would be the next sequence of numbers? my name is sharon i work in customer service and a friend asked me to solve this.

Walter Whiteley lui répond.

Intersection of perpendicular cylindrical surfaces 2001-07-31

Charlie pose la question :
Please consider two right circular cylinders, perpendicular one to the other, and of unlike radii in a 3 dimensional Cartesian space with mutually perpendicular x,y,z axes. If one cylinder is centered on the y axis with radius ra, and the other on the z axis with radius rb, then the expression for the first surface would be x² + z² = ra², y = any number. Likewise, the second cylinder's surface would be x² + y² = rb², z = any number.
It is my intent to define the curve at the intersection of these two cylindrical surfaces. From sketching the conditions it appears that this intersection resembles an ellipse folded about its minor axis.

Chris Fisher lui répond.

A trig identity 2001-07-27

Jeff pose la question :
prove this identity and show steps
tan(x/2+pi/4)=secx+tanx
Harley Weston lui répond.

Generating uniquie 2 digit numbers 2001-07-16

Anthony pose la question :
What methodology can I use to generate uniquie 2 digit numbers from unique 7 digit numbers. Of'course the total number of 7-digit numbers is not greater than 99.
Penny Nom lui répond.

Arclength of an ellipse 2001-07-03

A hobbyist pose la question :
What is the equation (with the length of the arc as a variable) for one quadrant of the ellipse,...
Claude tardif lui répond.

Securing a plank in four dimensions 2001-06-06

Becca pose la question :
If it takes two nails to secure a plank from rotating on a wall in the third spatial dimension, how many nails would it take if you were attempting to secure the board from rotating in the fourth spatial dimension?
Walter Whiteley lui répond.

Conservation, consumption and population growth 2001-06-04

Steve pose la question :
I'm trying to quantify the relation between conservation/consumption and population growth. For instance let's consider California:
The 2000 census states that California's population grew from 29,760* in 4-1990 to 33,871 in 4-2000. I want to find r or rate of growth per year. Based on the exponential growth formula for population growth:
.
.
.

Penny Nom lui répond.

SPRT 2001-05-24

A researcher pose la question :
I have a medical-pharmaceutical study that says:
SPRT (something to do with Secuential and Truncated).

Do You know what it means S.P.R.T. and what it is?

Ejaz Ahmed and Penny Nom lui répond.

The diameter of an oval 2001-05-23

Tim pose la question :
Is there a such thing as a diameter of a oval? If not, is there a way to get the circumference?
Claude Tardif and Penny Nom lui répond.

Harmonic numbers 2001-05-23

Leslie pose la question :
The harmonic numbers H_k, k = 1,2,3.....are defined by H_k = 1 + 1/2 + 1/3....1/k
I am trying to prove by mathematical induction:

H_2ⁿ >= 1 + n/2 , whenever n is a nonnegative integer.

H₈ = H_2³ >= 1 + 3/2

Can you help?

Harley Weston lui répond.

Circles, ellipses, parabolas and hyperbolas 2001-05-09

Colleen pose la question :
How is an ellipse like a circle?
In what way does an ellipse have a center?
How is a hyperbola similar and different to an ellipse?
How is a parabola similar a different to a circle ellipse and parabola?
Pnny Nom lui répond.

Tiling a floor 2001-05-01

Sarah pose la question :
Cut out of paper or cardboard a quadrilateral having no two sides parallel, no two sides of equal length and no indentations. Can an endless floor be tiled with copies of such a figure?
Claude Tardif lui répond.

A sequence defined recursively 2001-05-01

A student pose la question :
A sequence s is defined recursively as follows:
s₀=1
s₁=2
s_k=2s_k-2 for all integers

- Compute s2,s3,s4... to guess an explicit formula for the sequence sk.
Penny Nom lui répond.

A sequence of even terms 2001-04-29

A student pose la question :
A sequence c is defined recursively as follows:
c0 = 2
c1 = 4
c2 = 6

ck= 5ck-3 for all integers

Prove that cn is even for all integers.

Leeanne Boehm and Penny Nom lui répond.

A Taylor series 2001-04-27

Karan pose la question :
Given the following information of the function

f''(x) = 2f(x) for every value of x

f(0) = 1

f(0) = 0
what is the complete Taylor series for f(x) at a = 0
Harley Weston lui répond.

Geometry 2001-04-21

Rebecca pose la question :
How do you prove the following:
Let CD be an altitude of triangle ABC and assume that angle C=90 degrees. Let r1 and r2 be the inradii of triangle CAD and CBD, respectively, and show that r+r1+r2=CD, where r is the inradius of triangle ABC.
Chris Fisher lui répond.

Where do the lines y=2x-4 and y=x-1 intesect? 2001-04-06

Bryce pose la question :
solve the following problem by setting them equal to each other. Solve for x and y. Where do the lines y=2x-4 and y=x-1 intesect?
Penny Nom lui répond.

An emergency response station 2001-03-29

Tara pose la question :
Three cities lying on a straight line want to jointly build an emergency response station. The distance between each town and the station should be as short as possible, so it cannot be built on the line itself, but somewhere east or west. Also, the larger the population of a city, the greater the need to place the station closer to that city. You are to minimize the overall sum of the products of the populations of each city and the square of the distance between that city and the facility. City A is 6 miles from the road's origin, City B is 19 miles away from the origin, and City C is 47 miles from the origin. The populations are 18,000 for City A, 13,000 for City B, and 11,000 for City C. Where should the station be located?
Claude Tardif and Penny Nom lui répond.

An elliptic tunnel 2001-03-24

Janna pose la question :
A tunnel is built under a river for a road 12m wide with a 2m sidewalk on either side. The top of the tunnel is semi-elliptical. A local bylaw stipulates that there must be a clearance of at least 3.6m at all points on the road. If the smallest possible ellipse is used, find the clearance at the center of the road.
Harley Weston lui répond.

The repetend in repeating decimals 2001-03-21

Sharon pose la question :
What is the name for the bar over the repetend in repeating decimals? Also, what is the name of the long division "house"?
Penny Nom lui répond.

Timing with hour glasses 2001-03-20

Nathan pose la question :
How can a chef use an 11 minute hour glass and a seven minute hour glass to time a vegtable that needs to be steamed for 15 minutes.
Leeanne Boehm lui répond.

4160 2001-03-07

Jessica pose la question :
The product of two consecutive page numbers in this book is 4160. What are the page numbers?
Penny Nom lui répond.

Law of cosines 2001-02-20

Emily pose la question :
I missed a few days of class and I can't figure out how to solve Law of Cosines problems. I have the notes and formulas but I can't figure out how to do the math involved to answer the problems. I am also getting confused about how to use degrees and seconds in the Law of Sine and Cosine. I can't seem to get the correct answers and I don't really know how to solve them and enter them into my TI 86.
Harley Weston lui répond.

Percentage increase 2001-02-17

Bob pose la question :
If sales for jan 2001 are 154 vs 105 for 2000 - the increase total presented to my office is +46% - how does that compute. Please give me the equation.
Penny Nom lui répond.

Partitioning of an arbitrary line segment 2001-02-08

David pose la question :
Did Euclid's Geometry include a construction for the regular partitioning of an arbitrary line segment?
Chris Fisher lui répond.

23 + 17 * 2 / 8 + 11 = 13 2001-02-02

David pose la question :
My child is working through basic operations, and gave this problem:
23 + 17 * 2 / 8 + 11 = 13

The teacher wants the parenthesis to be put in the right places to come up with 13.
Claude Tardif lui répond.

Subsets of the natural numbers 2001-01-30

Christina pose la question :
How do I explain why the set of natural numbers (N) cannot be equivalent to one of its finite subsets?
Penny Nom lui répond.

Crossing the dessert 2001-01-29

Zach pose la question :
An Explorer needed to make a 5 day trip across a dessert. Each man with him could carry exactly 3 days food and water. For one man how many men will it take to cross the dessert?
Claude Tardif lui répond.

Geometric and arithmetic sequences 2001-01-26

Garry pose la question :
what are the equations for geometric and arithmetic sequences?
also, what are the equations for finding the sums of those series?

Leeanne Boehm and Penny Nom lui répond.

0,2,3,6,7,1,9,4,5,8 2001-01-23

Tami pose la question :
What is the sequence of the numbers 0,2,3,6,7,1,9,4,5,8
Claude Tardif lui répond.

The hypotenuse of a right triangle 2001-01-22

Phillipe pose la question :
How do you find the hypotenuse of a right triangle?
Penny Nom lui répond.

Proportionality: direct and indirect 2001-01-18

Nancy Ellis pose la question :
What is the difference between directly proportional and indirectly proportional?
Leeanne Boehm lui répond.

Polynomials and exponents 2001-01-15

A student pose la question :
I am duing a project in math on polynomials and exponents. I need a real life usage of polynomials and exponents for my project.
Penny Nom lui répond.

Some terms in a sequence 2001-01-15

jamie pose la question :
Please help as soon as possible! i am stuck with some terms in a sequence. the terms are 1st term=1, 2nd term=10, 3rd term=35, 4th term=84, 5th term=165, 6th term=286. can anyone tell me the formula for the nth term? n is term number
Sukanta Pati lui répond.

cot(arcsin 3/5) 2001-01-07

Jason pose la question :
Find value. Assume that all angles are in Quadrant 1.
cot(arcsin 3/5)

Harley Weston lui répond.

The city transit system 2001-01-07

Jacky pose la question :
The city transit system carries an average of 9450 bus riders a day, for a fare of $1.75 each. The city wants to reduce car pollution by increasing ridership and to maximize the transit system's revenue at the same time. A survey indicates that the number of riders will increase by 150 for every $0.05 decrease in fare.
Harley Weston lui répond.

Derfs, Enajs and Sivads 2001-01-07

John and Norman pose la question :
All Derfs are Enajs. One-third of all Enajs are Derfs. Half of all Sivads are Enajs. One Sivad is a Derf. Eight Sivads are Enajs. The number of Enajs is 90. How many Enajs are neither Derf nor Sivad?
Penny Nom lui répond.

A quarter-circle and two semi-circles 2000-12-31

Christopher pose la question :
Inside the quarter-circle are two semi-circles with the same radius, (r). Which has a greater area, G or L?
Penny Nom lui répond.

An infinite series 2000-12-16

John pose la question :
summation(n=1 to infinity)[n sin(1/(2n))]ⁿ
Harley Weston lui répond.

Direct and inverse variation 2000-12-12

Ashley pose la question :
I'm stuck on this unit of direct and inverse variation..please and my problems and show me how to do each PLEASE!!!
Assume that y varies directly as x

If y= -4 when x = 2, find y when x= -6

Assume that y varies inversely as x
If y =-4 when x=2, find y when x =-6

Penny Nom lui répond.

A point that a group of lines pass through 2000-12-05

Ross pose la question :
A point that a group of lines pass through is called a________?
Chris Fisher lui répond.

Triangles and trigonometry 2000-11-30

Mose pose la question :
If I have a right triangle, and I know the lengths of all three sides, is there a formula that will allow me to determine the measurements of the 2 non right angles?
Harley Weston lui répond.

Power series representations 2000-11-27

Grace pose la question :
Is there a systematic way of finding a power series representation of a function? I understand that you have to manipulate the function so that it is of the form 1/(1-x), but beyond that I am lost.
Harley Weston lui répond.

A piecewise linear equation 2000-11-24

Jacky pose la question :
There is a light bulb and it is given that the light bulb cost $0.75 and the cost of operating it is $0.0081 per hour. From the information give, I came up with the linear equation: Let c be total cost and Let h be hours used. Therefore: c = 0.0081h + 0.75 represents the total cost of the light bulb and the electricity. However, the second part of the question added the fact that the light bulb will only last for 800 hours. If the light bulb is replaced as soon as it burns out exactly after every 800 hours, how can I write an equation that represents that? Is it possible? What would it look like on the graph.
Harley Weston lui répond.

Comparing an integral and a sum 2000-11-21

Douglas Norberg pose la question :
A fellow teacher asked me about a problem she wanted to give to her students. It involved whether to take a million dollars or a penny doubled a number of times. I was able to determine the number must have been .01 * 2³⁰ which is about $10 million and a lot more than $1 million. To check that I was right I used a spreadsheet and did a Riemann sum.

When I finished I reasoned that I had done the task in several steps and I could have done it in 1 step. Thus I integrated .01 * 2^x from 0 through 30 but the number I got was $15,490,820.0324. Why the difference?

Harley Weston lui répond.

Range of a function 2000-11-21

David Bell pose la question :
Given a rational function such as f(x) = (8x-3)/(4x-1). How can the range be found.
Penny Nom lui répond.

Infinite Geometric Series 2000-11-10

Sam Carter pose la question :
I ran into a problem when studying how to find the sum of an infinite geometric series. My math book attempts to explain the concept by giving formulas involving sigma and |r|, but it does not really explain how to go about finding the sum of an infinite geometric series. If you could either help me with this or point me in the direction of an informative website that could help me, I'd appreciate it.
Harley Weston lui répond.

Rhombuses 2000-11-07

Melissa pose la question :
What in real life is the shape of a rhombus?
Chris Fisher and Walter Whiteley lui répond.

False Positives 2000-10-29

James pose la question :
A rare disease infected 1 in 1000 people in the population. A test for the disease is accurate 99% of the time when given to an infected person and also when given to a heathy person.

Fill out a two-tier tree diagram and find the probability of the false positive(i.e the conditional probabily of being healty even when tested postive by the test) Comment on the result?

...

Penny Nom lui répond.

Overlapping a circle and a square 2000-10-28

Jacky pose la question :
A square with a dimension 20 by 20cm. and a quarter of the circle with the radius of 25cm (A quater of a circle is created by 2 cuts that are perpendicular bisectors of each other where the intersecting point is at the centre of the circle). With these 2 pieces, the 2 pieces are placed over each other in which the 90^o angle of the quarter circle matches with one of the right angles on the square. Now, calculate the overlapping area of the 2 figures.
Chris Fisher and Harley Weston lui répond.

Find the rule 2000-10-27

Kelsa and Linda pose la question :
Find the rule: It had 13 in a circle then 2 blank circles then 31 in a circle then two more blank circles. Could you please help us.
Penny Nom lui répond.

Assessment and portfolios relating to math 2000-10-24

Jackie pose la question :
I will be assisting in a presentation for grades 4-6 on assessment and portfolios relating to math. If anyone has some ideas will love to hear them. I have checked out a few sites on the net
Diane Hanson lui répond.

A sequence question 2000-10-23

Chell pose la question :
I have the following sequence:
4 16 37 58 89 145 42 20

I have no clue how to arrive at an answer. I've checked to see if it can be defined as an arithmetic or geometric series, and it can't. I've looked for primes and noticed that 37 and 89 are the only primes ... but from there I've lost. Nothing I've tried seems to work, so please help! Thanks a million!!!!

Chris Fisher lui répond.

Concavity 2000-10-22

Alex pose la question :
the question is: on what interval is f(x)=(x²)(e^x)?
ive found the 2nd derivative which is e^x(x²+4x+2) and i did the quadratic to get -2-2^0.5 and -2+2^0.5, but i dont know what the interval is.
Harley Weston lui répond.

Sunflower seeds 2000-10-09

A parent pose la question :
Find the number of 3/4 pound of sunflower seeds that can be filled with 225 pounds of sunflower seeds
Penny Nom lui répond.

Maclaurin series again 2000-09-23

Jason Rasmussen pose la question :
I suppose my confusion comes into play when I am trying to figure out where the xⁿ term comes from. I know that the Power Series notation is directly related to the Geometric Series of the form sigma [ brⁿ ] where the limit is b/(1-r) for convergence at | r | <1. Therefore, the function f(x) needs to somehow take the form of b/(1-(x-a)), which may take some manipulation, and by setting r = (x-a) and b = C_n, we get the Geometric Series converted to the Power Series. Taking the nth order derivative of the Power Series gives C_n = fⁿ(a)/n!. There must be a gap in my knowledge somewhere because I cannot seem to make f(x) = e^x take the form of f(x) = b/(1-(x-a)). Maybe I should have labelled my question as "middle" because it may be more of a personal problem with algebra and logarithms. Or, am I to assume that all functions can be represented by sigma [fⁿ(a) * (x-a)ⁿ / n!]?
Harley Weston lui répond.

A Maclaurin series 2000-09-21

Jason Rasmussen pose la question :
I have a question regarding power series notation for certain functions within the interval of convergence.
Harley Weston lui répond.

Arithmetic in base 5 2000-09-20

Lesley Emerson pose la question :
my daughter is 9 and has been aske to solve the following in base 5

3+2
4+10
.
.
.
Penny Nom lui répond.

A proof that 1=2 2000-09-19

sporky pose la question :
Why does the proof for 1=2 not work?
x = 1
x² = 1
x = x²
1 = 2x (derivitive)
1 = 2(1)
1 = 2 ???

please tell me where the false logic is.

Walter Whiteley lui répond.

Tessellations 2000-09-17

Lindsay pose la question :
What is the word that means a shape repeated over and over again to make something like a quilt pattern?
Note: I'm pretty sure it is either a fractal or tesselation. Could it be that the pattern itself is a fractal but the entire quilt would be a tesselation?

Chris Fisher lui répond.

7 - - - - 77 2000-09-13

Peter pose la question :
Does anyone know how to solve the following:
7 _ _ _ _ 77 ?
I have to find the missing values.

Chris Fisher and Walter Whiteley lui répond.

The sum of the squares of 13 consecutive positive integers 2000-08-25

Wallace pose la question :
Prove that it is not possible to have the sum of the squares of 13 consecutive positive integers be a square.
Harley Weston lui répond.

Covering 1, 1/2, 1/3,... 2000-08-22

Wallace pose la question :
Consider the points 1, 1/2, 1/3, ... on the real number line. You are given five small bars, all of length p, which are to be placed on the number line such that all points will be covered. What is the minimum value of p that will allow you to do this?
Penny Nom lui répond.

Three consecutive odd integers 2000-08-18

Wallace pose la question :
A six-digit integer XYXYXY, where X and Y are digits is equal to five times the product of three consecutive odd integers. Determine these three odd integers.
Paul Betts lui répond.

A semi-circle and a triangle 2000-07-28

Ben pose la question :
A semi-circle and an isosceles triangle ABC have the same base AB and the same area. The equal angles in the triangle are BAC and CAB. I have to find the value of each of these angles.
Harley Weston lui répond.

Patterning and Sequencing 2000-07-05

Michael Jellis pose la question :
What would be the next two terms?
1.0,0.5,0.6,0.75,0.8,___,____

please explain!!! I am completely baffled and need all the help I can get!

Claude Tardif lui répond.

Cairo tesselation and Archimedean duals 2000-06-21

Joyce DuVall pose la question :
I am looking for a picture of the Cairo tesselation, and pictures of the Archimedean duals. Do you know of any good web sites or books?
Penny Nom lui répond.

A sequence 2000-06-16

Claire Hall pose la question :
Can you find the formula for the pattern 4,12,24,40,60
AClaude Tardif lui répond.

1+4+9+16+...n^2 = n(n+1)(2n+1)/6 2000-06-01

Shamus O'Toole pose la question :
How do you derive that for the series 1+4+9+16+25.. that
S(n)=(n(n+1)(2n+1))/6

Penny Nom lui répond.

Using the inverse sine function 2000-05-31

Nelson Rothermel pose la question :
This has me completely baffled. I have to use the laws of sine or cosine to find the angles of a triangle when I have 3 sides, so I can't go 180-x-y when I have 2 angles. Now, I have a triangle with values of 3, 7, and 9. Here are the steps I used (A,B,C are angles; a,b,c are opposite sides):
angle A (16.1951 degrees): cos^-1*((b²+c²-a²)/(2*b*c))
angle B (40.6011 degrees): sin^-1*(b*sin(A)/a)
angle C (56.7962 degrees): sin^-1*(c*sin(A)/a)

If you notice, A+B+C does not equal 180. According to the book, A and B are correct, but C is supposed to be 123.2038 degrees. Why doesn't it work???

Harley Weston lui répond.

Calculus Research Questions 2000-05-22

William Wright pose la question :
I am a Calculus Teacher, and me and my class ran into these two problems without solutions in my manual, we got answers, but are unable to check them. If anyone gets this email and can respond to this with the solutions it be greatly appreciated.
.
.
.
Harley Weston lui répond.

The number of seats in an auditorium 2000-05-16

David Evaska pose la question :
There are 10 students in the first row of seats in an auditorium 12 in the second 14 in the third and 2 additional in each seat. The total number of rows is 40. I know the answer is 1960 can you please show me the formula step by step.
Penny Nom lui répond.

Looking for a pattern 2000-05-08

Laura pose la question :
Yesterday, me teacher stumped me with a question. He talked to us about square units. He told us an area of 1 square unit produces 1 shape, an area of 2 sq.units produces 1 shape, an area of 3 sq.units produces 2 different shapes, an area of four square units produces 5 different shapes, and an area od five sq.units produces 12 different shapes. He left us there. He said we had to find how many different shapes an area of 1 sq. unit produces through how many different shapes an area of 15 sq.units produces. He said we could complete this "chart" by finding an equation. But, I can't find the equation. I think it may be a quadratic of some sort. My teacher told us to use the area(in sq.units) as X and the # of different shapes produced as Y. Now, what really is stumping me is I would have to have an equation so when X is Y, Y is 1 and when X is 2, Y is 1. I have also tried to see if I can complete a patter or something. The pattern I saw was 1,1,2,5,12. I can't make much sense of that pattern.
Penny Nom lui répond.

Area of an ellipse 2000-05-02

Kaushal Shah pose la question :
How do I Calculate the area of a ellipse known the length of any related thing. Example, suppose if I know the length of latus rectum, major&minor axis etc.
Walter Whiteley lui répond.

Two calculus problems 2000-05-01

Kaushal Shah pose la question :
How Do WE Integrate the following Functions,

Integral xtanx dx
How was natural base "e" discovered and why e=2.7.......

Claude Tardif lui répond.

Graphing cube roots 2000-04-27

Heather Jones pose la question :
What do the graphs of cube roots look like?
Walter Whiteley lui répond.

Paying with silver 2000-04-26

Luther Jackson pose la question :
A silver prospector is unable to pay his March rent in advance. He owned a bar of pure silver, 31 inches long, so he made the following arrangement with his landlady. He would cut the bar, he said into smaller pieces. On the first day of March he would give her and inch of the bar, and on each succeeding day he would add another inch to her amount of silver. She would keep this silver as security. At the end of the month, when the prospector expected to be able to pay his rent in full, she would return the pieces to him.
.
.
.
Claude Tardif and Penny Nom lui répond.

Sample variance 2000-04-16

Jonathan Freeman pose la question :
I was just reading your article entitled "A Note on Standard Deviation" I'm now teaching a unit on s.d. and my students were wondering why one uses a denominator of n for a population and n-1 for a sample. I saw in your article that this is because "[the quantity] tends to underestimate sigma... and other technical reasons." To which my students again asked... "Why?" Could you please elaborate a bit on the "other technical reasons" perhaps in terms a high school senior (or their teacher...) could understand?
Harley Weston lui répond.

Infinite sets 2000-04-12

Brian Provost pose la question :
Here's the deal: There are an infinite amount of integers (1,2,3...). Agreed? There are an infinite amount of even integers, too (2,4,6...). Agreed? By convention, infinity equals infinity. Yet common sense tells us there are obviously more integers than there are even integers. Prove this to be true mathematically.
Harley Weston lui répond.

Geometric sequences 2000-04-11

Jodie pose la question :
I am in a grade ten principles class and was taught how to do geometric sequences and series but no one in my class understood what we were taught. Our teacher is one of few to use the new curriculum which used to be the grade twelve curriculum. Could you please explain to me how to do geometric sequences and how to find the different terms and sums. Thank you very much!
Harley Weston lui répond.

Increasing the weight 2000-03-23

Lee Millard pose la question :
A weight of dimension a, b is to have its weight increased by w% by bolting plates of the same material along the top and one side (but not at both ends). The top plate and side plate have the thickness, x. Find the thickness of the plates for a given weight increase of w%.
Penny Nom lui répond.

Rule of 78 2000-03-22

Dan Baumgarten pose la question :
Can you explain the rule of 78 and the reverse rule of 78? Thanks.
Claude Tardif lui répond.

Completing a sequence 2000-03-17

David Grimmer pose la question :
Complete the following sequence so that, after the first two terms, each successive term is the average of all the preceding terms.
20__ __ 28 __ __

Penny Nom lui répond.

Angle of Intersection of Two Lines 2000-03-02

Veronica Patterson pose la question :
I am having a real hard time trying to figure out this problem. Could you please help me! The homework question says to find the acute angle of intersection between the two lines y=3x+1 and y=(1/2)x-1. (It also says to use the results of a problem I had already figured out.) That problem was to use information from a picture shown that tan(theta sub1-theta sub2)= ((m sub2- m sub1)/(1+(m sub1 * m sub2))). I used the difference identity of tangent to figure out the answer. Any help on this problem would be greatly appreciated.
Harley Weston lui répond.

What's the next term? 2000-02-29

Meredith O'Neill pose la question :
At this point, the whole family wants to know the answer. if possible an explanation. thanks
a sequence ?
16,37,58,89,145 ??

Chris Fisher lui répond.

Why counterclockwise? 2000-02-21

Drew pose la question :
Why do the numbers of quadrants in a graph increase in a counter clockwise pattern? Why aren't they numbered increasingly in a clockwise pattern?
Chris Fisher lui répond.

Perimeter of an ellipse 2000-02-21

Kurtis Proffit pose la question :
What is the formula for the perimeter or circumference of an ellipse?
Chris Fisher lui répond.

Number sense 2000-02-17

A college student pose la question :
I am a college student and I am to answer the following question: Describe ways of telling by simple inspection when a fraction has a value close to 0; close to 1/2; and close to 1. I am to imagine that I am a 3rd grader answering this question. Any thoughts please?
Penny Nom lui répond.

Play ball 2000-02-03

Jessie pose la question :
Here's a calc question that is probably a lot easier than I am making it. If you have a legendary "baseball problem" for the related rates section of Calc I, and you are given that the runner is running from 2nd to 3rd base at a given rate, and the umpire is standing at home plate, and you are given the distance between the bases on the field, how do you find the rate of change of the angle between the third base line (from the point of the umpire) and the runner? Here is a sample prob: Runner is moving from 2nd to 3rd base at a rate of 24 feet per second. Distance between the bases is 90 feet. What is the rate of change for the angle (theta, as described previously) when the runner is 30 feet from 3rd base?
Harley Weston lui répond.

100% on two tests 2000-02-01

Craig and Chelsea Bruzzone pose la question :
A class of 35 students took a math test and a science test. 12 students got 100% on the math test. 9 students got 100% on the science test. There were 19 students who made less than 100% on both tests. How many students made 100% on both tests?
Penny Nom lui répond.

Percent of improvement 2000-01-30

Steve Quigg pose la question :
In a 1998 survey, 21% polled responded favorably to a question. In 1999, 31% responded favorably.
What is the percent of improvement?

Harley Weston lui répond.

zero 2000-01-01

Jason pose la question :
What civilization first used zero?
Penny Nom lui répond.

Graph of a sine function 1999-12-23

Pierre pose la question :
Given;
amplitute:1
period: 540
Phase shift: 60 degree,right
I am ask to right the equation: sin 2/3 (value -60degree)
When I am asked to graph the equation, the period is mixing me up.
Harley Weston lui répond.

Approximations 1999-12-20

Adrian Valc pose la question :
Long-time ago I red an article about surprizing (and in a way frustrating) results in math, for example the limit of a nicely defined infinite series which was believed to be a simple rational number, but later was determined to be a transcendent number that missed the rational value by an incredibly small amount (so for example the limit proved to be 2.75000...00137.. with a lot of 0's in between). I cannot find that article anymore, so i was wondering if you have any such examples, or you can point to any relevant information source?
Chris Fisher lui répond.

Comma as decimal separator 1999-12-18

Franck Menuge pose la question :
Could somebody tell me the origin of the use of a 'comma' as a decimal separator and of a 'dot' for thousands in the French numeric system, ex.1.234,56 Is it only used in France or in other european coutries? Why is it different in the UK?
Patrick Maidorn and Penny Nom lui répond.

Rectangular hyperbola 1999-12-15

Aarti Chand pose la question :
Why do they call a rectangular hyperbola, rectangular and where the normal hyperbola looks like a rectangle and the rectangular hyperbola looks like a sqaure?
Chris Fisher lui répond.

.400 in Baseball 1999-12-15

Nieve Nielson pose la question :
I have several questions to ask about the probability of getting a .400 in baseball:

What is the probability of a baseball player hitting a .400 in one game, considering that the hitter is up to bat four times?

What is the probability of a baseball player hitting a .400 in a season, considering that there are 100 games in a season? With the first two questions in mind:

Considering that baseball has been around for about 100 years, about how many people should hit .400 inthat time?

Chris Fisher lui répond.

Two conics 1999-12-07

Quinn pose la question :
I know the formula to find the axis of symmetry of a conic section (I'm not sure what shape - circle for the first one??) is (-D/2A,-E/2C) but I obviously don't get how to calculate it, because when I check the answer it's wrong, but I'm so close!! For the following equations my teacher suggested to "divide the x term coefficient, D, by the x squared term coefficient before...do the same for y."
2x²+2y²-8x+12y+16=0
.
.
.
Penny Nom lui répond.

Bases other than 10 1999-12-06

Garret Magin pose la question :
We are doing a lesson on numbers of other bases than 10. We are working with binary, octal, and Hexadecimal. I was wondering what is used to represent number of different bases other then 16? Does it just continue on with the alphabet and if so what happens when you get to Z. It would be a help if you could answer this because it is really bugging me. And none of the math teachers at my school could let me know.
Claude Tardif and Patrick Maidorn lui répond.

Cos x = -1/2 1999-12-01

Pierre Boivin pose la question :
When I factor[ 2cos (square) - 5cos -3], I get (2cos + 1)(cos - 3). 2cos + 1 = 0, 2cos = -1, cos = -0.5,. Using inv cos on calculator, I get 120 degree related angle.
When I graph I get two values, between 90 and 180 degree and between 180 and 270 degrees. How do I find those two values. How do use 120 degree in relation with the x axis.
Penny Nom lui répond.

Selecting some players 1999-11-20

Korbin Brown pose la question :
Roger Craig, during his term as team manager of the San Francisco Giants, received a strange communication from the team general manager, Al Rosen. Mr. Rosen told him to select 25 players according to this formula: 1/2 of the team had to be outfielders and infielders 1/4 of the team had to be starting pitchers 1/6 of the team had to be relief pitchers 1/8 of the team had to be catchers Roger was a bit confused by Al's request, yet complied anyway. How did he do it?
Claude Tardif lui répond.

Domain and Range of a Function 1999-11-14

Michelle Mellott pose la question :
How do you find the range of the following function:
2y²/(y²+5y+6)??
I know the domain is x not equalled to -2, -3. How can one easily find the range?
Harley Weston lui répond.

Number sequences 1999-11-11

Justin Schessler pose la question :
I CAN NOT figure out this sequence or how we continue this sequence...
3,2,6,5,15,14,___,___,___
Chris Fisher and Harley Weston lui répond.

Inverses of functions 1999-11-01

Leanne Hickey pose la question :
Let f(x) = 2x² -3x + 2. Find f^-1(4) given the fact that f(2) = 4. So the question is finding the inverse of 4, he said it's easier than it looks.
Penny Nom lui répond.

Ben's observation 1999-10-28

Emily Nghiem and Ben Rose pose la question :
As a teacher at a school called Educere in Houston, I have a ninth-grade student who discovered the following shortcut last year as an eight-grader. What he noticed is that given any two consecutive integers (or n and n+1 for any rational number greater than or equal to 2), the difference between their squares was equal to the sum of the two numbers.
.
.

Chris Fisher and Penny Nom lui répond.

Clockwise or Counterclockwise? 1999-10-27

Tim pose la question :
A particle moves around the circle x² + y² = 1 with an x-velocity component dx/dt = y

Find dy/dt

Does the particle travel clockwise or counterclockwise around the circle? Why?

Harley Weston lui répond.

Piecewise functions. 1999-10-20

Jenny pose la question :
How do you figure out a piecewise function by hand?
e.x.
( 2x (if x is not equal to 0)
f(x)=<
( 0 (if x is not equal to 0)
Harley Weston lui répond.

Percentage increase 1999-10-03

Ann Allen pose la question :
I am a a student in the 12th grade. I need to know how to calclulate the following: A percentage increase from 2.0% to 9.5% is what percentage?
Harley Weston lui répond.

Notation 1999-09-03

Judy Gray pose la question :
My name is Judy Gray. I guess the level on this would be about middle school, and I am an other!! I've been out of school for alot of years. I have a couple of questions, I guess.

What does an equal (=) with a slash through it mean? I put intersects, but I think I'm wrong.

What is the symbol of a small n? Only the symbol is wider. Example: If A = {1.2} B = {2,3} then what is A (n) B? Can you make sense out of that?

What is the equation of the y-axis?

Penny Nom lui répond.

Cleaning an Ellipse 1999-07-29

Mark Salter pose la question :
Hello hope some one can help. We need to clean an elipse and then paint it. We need to know the square foot of the job and the job is an elipse which rises 2 ft. is 12 ft wide and is 36 ft long.
Harley Weston lui répond.

A Weighty Problem 1999-06-17

A parent pose la question :
When using a balance scale, weights can be placed on either side of the scale. For example, if a 10 pound weight provides a counter balance to an object and a 7 pound weight, then the object must weigh 3 pounds. What four weights can be used to weigh objects of 1, 2, 3 ... 38, 39, 40 pounds?
Penny Nom lui répond.

Base 2 to Base 10, conversion, convert 1999-05-08

Larry Bader pose la question :
10100011₂ is the same as what number in Base ten?
a. 83
b. 128
c. 93
d. 326
e. 163
Penny Nom lui répond.

Shape-preserving transformations 1999-05-04

J McAndrew pose la question :
A shape preserves its shape if a rotation, translation or scaling is performed on it. Are these the only continuous transformations which have this property? These transformations if performed on the parts and then summed have the same effect as the transformation being applied to the whole; are these linear transformations? Who, and what area of mathematics has classified all transformations of this type completely?
Chris Fisher lui répond.

Radius of convergence 1999-04-21

Nowl Stave pose la question :
Why is the radius of convergence of the first 6 terms of the power series expansion of x^(1/2) centered at 4 less than 6?
Harley Weston lui répond.

A Series 1999-04-20

Deepak Shrestha pose la question :
Given the sequence an=e^(-n*Ln(n)), does the series converge and why?
Harley Weston lui répond.

Volume of oil in a tank 1999-04-17

Lars Waldemarsson pose la question :
My problem is to get an equation for the depth of the oil in a gastank formed like a cylinder. The cylinder is in a horizontal position and by a stick you will be able to get the depth of the oil in the tank. All I need is an exmaple which I can build on. By this equation you will be able to get the volume of the oil if you know the depth.
Harley Weston lui répond.

Dividing a Circle 1999-04-12

Mike Kenedy pose la question :
I am having trouble with a homework question for bonus marks. A Circle is continually divided by lines that do not intersect the center so that they produce the most pieces of circle. For example

1 line divides the circle into 2.
2 into 4.
3, however into 7.
4 into11
5 into 16
6 into 22
7 into 29
8 into 37
etc...
I am stumped and cannot figure out the equation, though I'm sure it involves squares. Can you help?
Penny Nom lui répond.

Cross-sectional area of a cylinder 1999-04-12

Rebecca Connor pose la question :
What is the formula to find the cross-sectional area of a cylinder?
Chris Fisher lui répond.

Linear programming and optimization 1999-04-09

Shams pose la question :
What is Linear programming and optimization?
Jack LeSage and Penny Nom lui répond.

Percentages 1999-03-16

Beth Barton pose la question :
If I have two figures and want to know the difference between them, in Percentage, how do I proceed with a calculation?
Example: 67,800 - 56,000 = 11,800
What percentage does this difference represent?
Jack LeSage lui répond.

Where three sequences meet. 1999-03-06

Ali pose la question :
My name is Ali and I am in the 5th grade.
I have a math question:
What is the least positive integer meeting each of the following conditions:

Dividing by 7 gives a remainder of 4

Dividing by 8 gives a remainder of 5

Dividing by 9 gives a remainder of 6

Help!
Denis Hanson lui répond.

Reversing the direction of an inequality. 1999-03-06

Mallory White pose la question :
If the Problem was -4a plus -5 is less than or equal to 14, why would you change the sign to greater than or equal to?
Jack LeSage and Harley Weston lui répond.

Finding a rule for a sequence 1999-02-17

Lindsey Masters pose la question :
I'm doing a maths investigation and i have a sequence which goes:-
13,16,25,32,45,56,73.
Our teacher told us we have to find a rule by looking at the differences of the terms until we find a constant. The first differences are:-
3,9,7,13,11,17.
The differences of these are:- ......
Please could you tell me how to work it out so that I could work out the rules of similar sequences.
Penny Nom lui répond.

Dig digs in the garden 1999-02-11

Katherine Shaw pose la question :
A circular garden has an a radius of 8m. Dig, the dog, is tied up to a fence that runs round the outside of the garden. Dig was able to dig up all the garden, apart from an area of 64 square metres, which he couldn't reach. How long was his lead?
Chris Fisher and Harley Weston lui répond.

Cannonballs 1999-01-27

Roger King pose la question :
How many cannonballs can be stacked in a triangular pyramid?
Penny Nom lui répond.

Place Value 1999-01-05

Reg pose la question :
I work in a Section 27 classroom with various grades. I am looking for assistance on how to deliver a lesson on place value:decimal numbers keeping in mind that they need to see it (visual) to comprehend. I am looking for grade 4-6 level.
Jack LeSage lui répond.

Intersection of Planes 1998-12-03

Lindsay Fear pose la question :
My name is Lindsay Fear. I am an OAC student (which is the Ontario equivalent to Grade 12 in most other states and provinces). I am in an Algebra and Geometry course and am currently studying a unit on equations of planes. Our teacher has given us this question that my friend and I have attempted several times, but we are still unable to solve it. My teacher has also suggested using the internet as a resource. The question is:
Prove that a necessary condition that the three planes
-x + ay + bz = 0 ax - y + cz = 0 bx + cy - z = 0
have a line in common is that
a^2 + b^2 + c^2 + 2abc = 1
Walter Whiteley lui répond.

Intersection of planes 1998-11-22

Dave Rasmussen pose la question :
I am a teacher of secondary mathematics with a question about the uses of Three Dimensional Co-ordinate Geometry. I have been teaching my students to write equations of planes and lines, - to find the intersection of these and the distance between them. What I am having difficulty finding are good applications of these techniques to "real world" situations. Can anybody help me?
Walter Whiteley and Harley Weston lui répond.

What's the next term? 1998-11-12

Ilia pose la question :
What the formula and explonation for formula for next patterns:
1) 1, 4, 10, 20, 35, 56, 84,...
2) 0, 6, 30, 90, 210, 420,...
Thanks!
Penny Nom lui répond.

Two sides and a bisectrix. 1998-11-11

Victor Grinshtein pose la question :
I am looking for someone who can tell me how to construct a triangle by 2 sides and a bisectrix using a compass and a ruler.
Chris Fisher lui répond.

Operations Research 1998-10-08

Lisa Barrett pose la question :
What is the history of operations research and the study of linear programming?
Judi McDonald lui répond.

Dividing a Class 1998-10-01

Tom Barker pose la question :
My eighth grade niece called with the following homework problem:
A teacher wanted to divide her class into equally numbered groups. She tried to divide the class into groups of two, but was one student short. She tried to divide the class into groups of five, but was one student short. She tried to divide the class into groups of seven and was successful. What is the least number of students that were in her class?
I know the answer is 49, but don't know how to prove it. I must be getting old if I can't solve eighth grade math problems. Your assistance would be appreciated.
Penny Nom lui répond.

Concurrent Lines in a Triangle 1998-08-10

Chris Woolf pose la question :
The question is Name four types of concurrent lines, rays, or segments that are associated with triangles.
Chris Fisher lui répond.

Social Security Numbers 1998-07-07

Valerie Lucas pose la question :
How many social security numbers are possible?
the answer is 10^9
why isn't the answer 9^9?
Harley Weston lui répond.

Sequences and series 1998-05-27

Michael Le Francois pose la question :
The sum of the first ten terms of an arithmetic series is 100 and the first term is 1. Find the 10th term.
The common ratio in a certain geometric sequence is r=0.2 and the sum of the first four terms is 1248 find the first term.
Penny Nom lui répond.

The Fourth Dimension 1998-05-24

Whitney Page pose la question :
Okay, here goes all my effort to try to explain shat I'm trying to ask of you. It's about something I read in a book called A WRINKLE IN TIME, by Madeline L'Engle. It's called tesser, or tesseract.
It talks about first diminsion, a straight line, second diminsion, a flat square, and third diminsion, a square with sides, front and back, top and bottom.
I can picture all of that. Then it says that fourth diminsion is when you square the three diminsional square. It also described the fourth diminsion as time. I can't figure out how that can be. Then it says...
Chris Fisher lui répond.

Multiplying by Nine - Chismbop Style 1998-04-27

Noria Jones pose la question :
About a year ago a grade 5 teacher at my son's school taught the children how to multiply the 9 times table on their fingers quickly.
It was part of a kind of finger math kind of thing...
Patrick Maidorn lui répond.

Seed Problem 1998-03-26

Jody A. Johnson pose la question :
Seed Problem: The height of an amazing plant grown from a seed varies linearly with the time it has been in the ground. After six days it is 6cm tall and after 60 days it is 15.8m (1580 cm) tall.

Write the particular equation giving the height as a function of time.
Find the intercepts and explain them.
What would be the height in one year?
How long would it take for the plant to grow to a height of 1km?
I'm having a problem with this equation. Could you please help. Thank you.
Penny Nom lui répond.

Matrices 1998-03-10

Ksya pose la question :

A and B are matrices. If A^n=B^n, can we say A=B or det(A)=det(B) or det(A)^n=det(B)^n ? Any conditions ???

If B^(-1) is the inverse of B, where B is a matrices. Can we say [(B^(-1))^n][B^n]=I, where I is identity matrices? Any conditions???

Doug Farenick lui répond.

Pay Phone Problem 1998-02-26

Shameq pose la question :
Hi, I've been given a problem that I'm having some trouble with. I'd really appreciate any help. Here's the question (it's called the Pay Phone Problem)
A pay phone will take only 10p, 20p, 50p, and £1 coins"(It's British).
A woman has plenty of 10p and 20p coins. She has no other coins. She can put the coins into the pay phone in any order.
INVESTIGATE the number of different ways, she could put the 10p and 20p coins into the pay phone.
Penny Nom lui répond.

Tessellations of non-polygons 1998-02-24

Ellen Goldwasser pose la question :
Hi! My name is Ellen Goldwasser. I'm a seventh grade student and I'm doing a prodject on tessellation. My question is: why will certain shapes (not polygons) tessellate? Thanks for your help!
Penny Nom lui répond.

Tangrams 1998-02-24

Allison pose la question :
Do you know the story behind the tangram? I know that it is a Chinese puzzle about 200 years old. If there is a story about its creation, I would love to share it with my 7th graders. Thanks.
Diane Hanson and Penny Nom lui répond.

Intersecting Lines. 1998-02-10

Erik Heppler pose la question :
My typewriter frequently makes mistakes. Suppose I gave you the following system of equations to solve:
35.26X + 14.95Y = 28.35
187.3X + 79.43Y = 83.29
When I looked back, I realized that I meant to use 14.96 as the "Y" coefficient in the first equation instead of 14.95. Solving the system using 14.95 and then solving another system using 14.96 with all other values the same both times results in the intersection points (1776, -4186) and (-770, 1816) respectively.
How can that be?
Penny nom lui répond.

Calculating the Intersection Point. 1997-12-10

Milton Parsons pose la question :
Given 2 lines through (x1,y1),(x2,y2),and (x3,y3),(x4,y4). Can you give me a good formula for calculating the intersection point. I would greatly appreciate it.Thanks.
Chris Fisher and Penny Nom lui répond.

How many intersections? 1997-10-08

James pose la question :
(a) A collection of eight points, no three collinear. If lines are drawn between each pair of these points, how many points of intersection would there be?
(b) what would your answer have been in part (a) if there had been n points to start with?
Chris Fisher lui répond.

Two Questions 1997-08-28

Faye Tan pose la question :
I am a trainee teacher. I would appreciate it very much if you could help me solve the following two problems which I think are meant for students at middle grade.
1. If a hen and a half lays an egg and a half in a day and a half, how many hens are needed to lay a dozen eggs in one day?
2. There are fewer than 200 passengers on a train. If they get off in pairs, one passenger will be without a partner. If they get off in groups of 3 or 4, there will still be one passenger left by himself. However, if they get off in groups of 5, no one will be left by themselves. How many passengers are there on the train?
Penny Nom lui répond.

Graphing Inequalities of Conic Sections 1997-03-24

James Sheldon pose la question :
I'm trying to graph Systems of Conic Sections with inequalities, but I'm running into problems on which area to shade:
x^2+y^2 is greater than or equal to 16
xy > 4
So I graph these two equations, and then my teacher said to substitute a point into it but I'm still not sure how to do it...
Penny Nom lui répond.

Area Between Two Sectors 1997-03-02

Rebecca Henry pose la question :
Points A,B,C,D,E,F are equally spaced on a unit circle. Arc CGE has a center A. Find the number of square units of area in the shaded region.
Walter Whiteley lui répond.

Some Circle Questions. 1997-02-25

Staci Vawser pose la question :
A circle with a radius of 10m is drawn. A chord is drawn across the circle. How is the area that is formed between the chord and the arc calculated?
Harley Weston lui répond.

Foci of an Ellipse 1997-01-22

David Gilliam pose la question :
How do I find the focii of the following equation? 4x^2 + 9y^2 = 36
Harley Weston lui répond.

Common Area of two sectors. 1996-11-06

Lynda Mow pose la question :
How do I find the area common to two intersecting circles of radii 8 ft and 10 ft if their common chord is 10 ft long?
Penny Nom lui répond.

Where do 2^x and x^2 intersect? 1996-07-23

Darin M Selfridge pose la question :
The intersecting points of y=2^x and y=x^2, graphed along with x^2=2^x, are obviously three... (2,4), (4,16) and (?,?). I am having problems figuring out the value, and even an equation for the (?,?). Can you help?
Harley Weston Chris Fisher lui répond.

What are fractals and are they of any practical use? 1996-06-26

Ron pose la question :
What are fractals and are they of any practical use?
Chris Fisher lui répond.

Converting to other bases 1996-02-06

Paul pose la question :
Converting base 10 numbers to other bases
Penny Nom lui répond.

What is the golden section? 1995-09-17

Cindy pose la question :
What is the golden section of a line?
Denis Hanson lui répond.

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Centrale des maths reçoit une aide financière de l’Université de Regina et de The Pacific Institute for the Mathematical Sciences.