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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.

Dérivée logarithmique 2007-03-04

Albert pose la question :
Déterminer la dérivée première des fonctions logarithmiques suivantes : 1) f (x) = x exposant x 2) f (x) = x exposant e exposant 2x
Claude Tardif lui répond.

logarithme 2006-10-24

Julie pose la question :
Loga(x^2-4) - loga(x-2)
Claude Tardif lui répond.

ln(x+3)+ln(x+2)=ln(x+11) 1999-11-24

Thibault Portevin pose la question :
"Résolvez l'équation : ln(x+3)+ln(x+2)=ln(x+11)" Je suis bloqué, pourriez-vous m'aider?
Claude Tardif lui répond.

logarithme neperien 1999-11-10

Louise Kieffer pose la question :
D'où provient la valeur e ( 2,7....) des logarithmes népériens ?
Claude Tardif lui répond.

A problem with logarithms 2019-08-23

Iriogbe pose la question :
Find the value : if log3 (a-6) =2b and log2 (a-7) =3b
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.

Double the number of pennies each week 2019-02-28

Donald pose la question :
If I save a penny a week,double it every week,How many weeks will it take to reach 1,000,000 dollars
Penny Nom lui répond.

y=lnx+(1+ln2)/2 and y=x^2 2019-01-28

Mike pose la question :
Prove that y=lnx+(1+ln2)/2 and y=x^2 touch each other.

The course is about logarithm and root functions... how should I solve this problem?
Penny Nom lui répond.

4444^4444 2017-12-10

Sashi pose la question :
4444 to power of 4444=?
Please share the result with simplification.
Penny Nom lui répond.

The derivative of f(x)=2^x/x 2017-11-28

Chhavi pose la question :
f(x)=2^x/x.
Find f'(x).
Penny Nom lui répond.

3^2x-5=27 2016-12-14

danaja pose la question :
solve for the following 3^2x-5=27
Penny Nom lui répond.

Find two values of x satisfying f(x)=1 where f(x)=sin(ln(x)) 2016-01-21

Ruth pose la question :
I'm trying to find two values of x satisfying f(x)=1 where f(x)=sin(ln(x))
Penny Nom lui répond.

Manipulating an expression using logarithms 2015-05-18

Katie pose la question :
Solve x=At^be^-ct for b in terms of c.
The e is Euler's number, not a letter or random placeholder.
v I've tried 2 methods on my calculator, and I am unsure as to why they give me different answers, and which one is correct.
For some reason, when placing a multiplication sign in between the A and the first t, I get a completely different answer. Why is this?
Also, which is the right answer for the question I have?
Thank you!
Katie :)
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.

Logarithms 2014-08-28

effaryna pose la question :
how logarithms is applied in everyday life?
Penny Nom lui répond.

Differentiate ln[x(2x-4)^1/2] 2014-06-28

Igwe pose la question :
If y=In[x(2x-4)^1/2],find dy/dx at x=3
Penny Nom lui répond.

How do we use logarithms in our daily life 2014-06-01

ss pose la question :
how do we use logarithms in our dailylife
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.

Evaluate log3 14 2013-11-17

Tash pose la question :
Use the Change of Base Formula and a calculator to evaluate the logarithm, correct to six decimal places. Use either natural or common logarithms.

log3 14
Penny Nom lui répond.

n log n = 36 * 10 ^ 12 2013-11-12

shihab pose la question :
How to find value of n in this equation :

n log n = 36 * 10 ^ 12
Penny Nom lui répond.

2^x . 5^3 = x^4 2013-09-05

Zuhdina pose la question :
Hi, I got a question, 2^x . 5^3 = x^4 I want to know the value of x without using calculator, I've already done some questions in logarithm and I always stuck in the same model equation-I think if someone shows me the way, I can do the other 'stuck equations'
Penny Nom lui répond.

4=(1+.08)^x 2013-06-15

Samantha pose la question :
I can't seem to understand how to solve for x when it is in power form, here is the equation:

4=(1+.08)^x
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.

Solve 8 logx > x 2013-02-19

Fulvio pose la question :
Hi, could you solve this equation in algebraic form:

8logx>x
Harley Weston lui répond.

What is the domain of f(x)=sin(ln(x))/ln(x)? 2013-02-06

Behrooz pose la question :
Hi, the following problem may be interesting: What is the domain of f(x)=sin(ln(x))/ln(x)? Be careful, domain is not obvious. Best regards Behrooz
Penny Nom lui répond.

The exponential form of log8=P 2012-04-25

Kristina pose la question :
what is the exponential form of log8=P
Penny Nom lui répond.

A log equation in exponential form 2011-11-11

Sarah pose la question :
Express the equation in Exponential form

log2 to the 16th power=4
Penny Nom lui répond.

Uses of logarithms 2011-11-09

BEA pose la question :
what is the use of logarithmic functions in real life or daily life?
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.

Exponential form 2011-05-18

Kara pose la question :
How do I write this in exponential form?

log 1/8 = -3
Penny Nom lui répond.

ln(12 x) = 6 2011-03-03

Carolyn pose la question :
solve the equation

ln12x = 6

Thank you

Carolyn
Penny Nom lui répond.

Daily life example of logarithms 2011-02-04

owais pose la question :
what are the application or daily life example of logarithms?
Harley Weston lui répond.

Simplify the logarithmic expression 2010-12-02

Adori pose la question :
Use the properties of logarithms to simplify the logarithmic expression. Log(1/250) base 5
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.

An equation involving logarithms 2010-09-27

mindy pose la question :
Hi,
I am trying to find x, the equation is:
log_2(log x + 2 (log x)^(1/2) + 1) - 2 log_4((log x)^(1/2) + 1) = 1

Thank you very much for your time. =)
Harley Weston lui répond.

A logarithmic equation 2010-09-08

Rohit pose la question :
x^2 + k*ln(x) - c - k = 0

Where k and c are constants.
Penny Nom lui répond.

y = - log(x) 2010-04-28

Alex pose la question :
y= - log(x), where y = 4.3
solve for x.
Harley Weston lui répond.

Log[f(x)] 2010-03-08

sourabh pose la question :
What is the number of solutions of the equation 9 x 2 - 18 x + 5 = 0 for x, such that the expression log10[(x+1)(x+2)] exists?
Harley Weston lui répond.

Growth rates 2010-01-26

Bhavya pose la question :
Dear Sir/Ma'am,

I read in the text book that the growth rates of these 3 functions are as below- n^2/3 < n/lg n < n^0.99

I tried the substitution method to check the correctness of this. But it gets really tough as n increase.

Is there any simpler way to understand the correctness of these growth rates?

Thanks and Regards,
Bhavya
Robert Dawson lui répond.

Exponential form 2009-08-05

motaz pose la question :
Let x = log_2 1/8 Write the exponential form of the equation and solve the equation for x
Stephen La Rocque lui répond.

Log_7 (4X) = Log_14 X 2009-07-08

Mukulu pose la question :
Help me with this question because i tried my level best to get the right answer but i failed Log_7 (4X) = Log_14X
Stephen La Rocque lui répond.

Possible Values of a Base of a Logarithm 2009-06-05

nazrul pose la question :
If log base x of 25=2 then what is the value of x? I am confused if the result be 5 or -5. Please explain. Thank you.
Robert J. Dawson lui répond.

(logx)squared + log (xcubed ) +2 =0 2009-05-19

michael pose la question :
Solve for x: (logx)squared + log (xcubed ) +2 =0
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.

An inequality with logs 2009-03-06

Indrajit pose la question :
(x/10)^(logx - 2)<100..........how to solve this one??
Stephen La Rocque lui répond.

If 5 to the power of y = 625, what is y? 2009-03-02

Charlene pose la question :
If 5 to the power of y = 625, what is y?
Penny Nom 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.

How do you solve "logx^4=4? 2008-11-17

Scott pose la question :
How do you solve "logx^4=4"?
Penny Nom lui répond.

Logs and exponentials 2008-10-06

Charles pose la question :
I seem to remember you could solve exponential problems using natural logs quite simply without calculators, such as the fifth root of 400 or 33 to the 4th power. All you did was convert the number to its natural log and then just divide by 5 or multiply by 4 and then convert it back. I just remember how to do this. Thanks.
Harley Weston lui répond.

Solving Exponential Equations Using Logarithms 2008-09-15

Todd pose la question :
7(6^x)=6e^-2x
Janice Cotcher lui répond.

2^x = 1,000,000 2008-09-06

Peter pose la question :
How do I solve for "x" in the following equation: "2 to the power of x = 1,000,000" ?
Penny Nom lui répond.

Solve e^x + e^(x+1) = 250 2008-08-25

Laura pose la question :
"solve this equation correct to three decimals"
e^x + e^x+1= 250
Penny Nom lui répond.

Write log_2 (1/8) = -3 in exponential form 2008-06-27

Jaime pose la question :
how do you write log2 (1/8) = -3 in exponential form?

the 1/8 is a fraction and the 2 is a base of 2
Penny Nom lui répond.

limit x->0 (logx-log(x-1)) 2008-05-22

kritica pose la question :
lt x->0 (logx-log(x-1))
Harley Weston lui répond.

Which is larger, 727464^512693 or 624610^518548? 2008-05-18

Yahweh pose la question :
Lets say I have two very large numbers in the form of a^b: 727464^512693 and 624610^518548

I want to calculate which number is larger, but its unreasonable to type these numbers into a spreadsheet to get an answer right away. How could I determine the larger or the two numbers efficiently?
Stephen La Rocque 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.

log2x+log(x+4)=1 2008-04-12

ryan pose la question :
solve the equation for x, log2x+log(x+4)=1
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.

ln (x) - x = ln (2) 2007-11-18

James pose la question :
How do you make x the subject of

ln (x) - x = ln (2)
Stephen La Rocque lui répond.

0 = (1/t) - [ln(1+r) ln(t)] 2007-10-18

Brandi pose la question :
Objective: solve for t, where r = 0.05

0 = (1/t) - [ln(1+r) ln(t)]
Penny Nom lui répond.

x= (y/z)ln((1+a^2)/(1-a^2)) 2007-09-26

John pose la question :
If x= (y/z)ln((1+a^2)/(1-a^2)) Please solve for 'a' Thanks in advance!
Penny Nom lui répond.

Logs and exponentials 2007-07-31

Marsia pose la question :
Explain how the functions of exponents and logarithms relate to each other.
Penny Nom lui répond.

The graph of a log function 2007-07-30

Marsia pose la question :
How would you describe to another student what the graph of a logarithmic function looks like?
Penny Nom lui répond.

log_a b + log_b a < 0 2007-07-08

Claire pose la question :
Suppose a, b are real numbers taking all positive values except 1, determine (without the use of calculators) whether there exists values of a and b such that log_a b + log_b a < 0
Penny Nom lui répond.

log(0.81) 2007-06-28

Ade pose la question :
If log 3 = 0.477 . The answer of log 0.81
Harley Weston 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.

Exponential form: x^y 2007-06-22

Kishor pose la question :
whats the easy way to calculate X raised to Y where y is much greater than x.
Stephen La Rocque lui répond.

Understanding log equations 2007-05-10

Sean pose la question :
The number, N, of people who have heard a rumor spread by mass media at time, t, in days is modelled by N (t) = a / 1+ be^ -kt. If 50 people have heard the rumour initially and 300,000 people hear the rumour eventually, find a and b. If the rumour is initially spreading at the rate of 500 people per day, find k.
Penny Nom lui répond.

What is the limit of 3.x^(3/x) as x approaches +infinity? 2007-04-11

Teodora pose la question :
What is the limit of 3.x^3/x as x approaches +infinity ?
Haley Ess lui répond.

Logarithms 2007-04-09

Emi pose la question :
Given log10 2=0.30 and log10 3=0.47 How to i express 6 x 10power 14 in logarithm answer. Please help me. Thank you. Emi
Stephen La Rocque lui répond.

A logarithm of a product and the product of logarithms 2007-02-27

Sharon pose la question :
Can you please explain Explain the difference between a logarithm of a product and the product of logarithms and give examples of each?
Stephen La Rocque and Penny Nom 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.

How many digits are in the number 2^64? 2006-06-14

Trang pose la question :
How many digits are in the number 2⁶⁴?
Stephen La Rocque lui répond.

An equation involving logarithms 2006-03-05

Chris pose la question :
Given that log_e y = 0.3log_ex+1.2 show that y=3.32 x^0.3

Penny Nom lui répond.

6^(x+1) = 12^(x-3) 2006-02-05

BB pose la question :
6^x+1 =12^x-3
Penny Nom lui répond.

Differentiation, powers and logs 2006-01-06

Claudia pose la question :
Question: how do I find the derivative of

x* ln(x+(e^2))^2

x^lnx

x^(e^(-x^2))

Penny Nom lui répond.

Express t as a function of d 2005-11-30

Matthew pose la question :
I have a problem on my homework I cant seem to figure out. Basically it gives me this Linear Regression Equation:

ln t=1.5 ln d-0.8954

and it wants be to transform the equation expressing t as a function of d. For some reason I keep getting it wrong. Anyone got an idea of how to do this?

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.

How many digits? 2005-06-07

Floren pose la question :
The numbers 2¹⁹⁸⁹ and 5¹⁹⁸⁹ are written one after another. How many digits in all are there?
Claude Tardif lui répond.

Logarithmic differentiation 2005-05-23

Richard pose la question :
I need to convince myself that I understand the process of differentiating y=x^x.
The specific question is that if I have to take the logarithm of both sides of the equation how can differentiate the following?
y= {(x+2)^(x+2)}/{(x+1)^(x+1)} - {(x+1)^(x+1)}/(x^x),
I have an idea that the differential of this fairly complex function is itself ... am I right or wrong.
Penny Nom 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.

Extraneous solutions 2005-02-04

Heather pose la question :
My teacher wants to know why there are extraneous solutions in logarithms?
Penny Nom lui répond.

Some logarithm problems 2005-01-27

Jo pose la question :
Given ln x=7.1; ln y=8.2, Find ln(x^3y^7)
Penny Nom lui répond.

ln(hx+n) 2005-01-07

Anibal pose la question :
if I have the eq. y=hx+n and I want to know ln(y), how do I process ln(hx+n)?
Penny Nom lui répond.

e = ln(b/a) solve for a 2004-12-01

Daniel pose la question :
I am trying to make "a" the subject of this equation "e = ln(b/a)" but am not sure if i'm doing it right. Any help would be appriciated,
Claude Tardif lui répond.

Two problems 2004-08-02

JJ pose la question :
A question on my homework assignment about logs says "suppose that x=logA and y=logB & write the expression in terms of x and y"

log(A - B)

Is this even possible? It seems like a typo.

Another is: "solve for t."

12(1.221)^t = t + 3

Is this one possible? If it is, I cant figure it out.
Penny Nom lui répond.

12(1.221)^t = t + 3 2004-07-14

Jay pose la question :
This problem has me stumped since i cannot separate the t and the 3. Here it is:

12(1.221)^t = t + 3

It's on a logarithm worksheet, but how do i figure it out?!
Harley Weston lui répond.

(ln(50/x)) / (ln(40/x)) = a 2004-06-21

Un eleve pose la question :
(ln(50/x)) / (ln(40/x)) = a = constante

comment extraire la variable x ???
Claude Tardif lui répond.

Logs 2004-02-29

Sandy pose la question :
find X
3/2logb4-1/2logb8+logb2=logbx

my book uses prop 7 to rewrite as logb4raised3/2-logb8raised2/3+logb2=logbx; then writes logb8-logb4+logb2=logbx how did it get here?
Claude Tardif lui répond.

A problem with logs 2004-02-22

Caitlyn pose la question :
problem: ln x + ln (x-2) = 1

I can solve this on the calculator, but the book wants 1+ [(sqroot)1+e]. How can I get the e?
Penny Nom lui répond.

Logarithms 2004-02-01

A student pose la question :
Where did the word logarithmic come from? Where/whom did it originate?
Harley Weston lui répond.

Domain of a function 2003-10-14

Karim pose la question :
Find the Domain of the Function
H(x) = Log3 (4x + 7)-10
H(x) = log base 3 times 4X plus 7 minus 10
i am having problem solving these kinds of problems.
Penny Nom lui répond.

Applications of logarithms 2003-09-16

A student pose la question :
I have a project due in my algebra two class dealing with logs and where they are used in life, but I am having trouble finding websites that relate. So I would really appreciate it if you couldhelp me.
Penny Nom lui répond.

Natural logarithms 2003-07-22

Amanda pose la question :
I'm going into my senior year of high school. I will be taking AP calculus, and my teacher gave us some homework over the summer. However, there are two things that I do not understand how to do. The first is, she wants us to be able to generate a unit circle by hand using 30, 60 and 90 degree triangles. I have used the unit circle in trigonometry, however I was never taught how to draw it. Secondly, I need to know how to do natural logarithms without a calculator. I was not taught how to do this, and the worksheet I was given only showed me how to complete them using a calculator.
Claude Tardif lui répond.

Solve x = y^z for z 2003-06-28

Nathan pose la question :
If x = y^z is there a way to solve for z, if x and y are given, without guessing or already knowing the answer?

ie: 64 = 2^z
6 is the obvious value for z. Is there a way I could solve for this variable using a formula, which would also apply when more complex values were substituted for x and y?
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.

The probability that the area of a triangle is smaller that 1/8 2001-12-21

Hoda pose la question :
Given unit square pick two points on adjacent sides of the square , what is the probability that the area of the resulting triangle is smaller that 1/8? I tried to tackle the problem by first sketching a square with the four vertices at (0,0), (1,1), (0,1) and (1,1). The answer seems to be the area under the curve y=0.25/x between 1 and 0, but how can you integrate such a function when ln0 is undefined? any help would be highly appreciated.
Andrei Volodin lui répond.

1996^1999 and 1999^1996 2001-07-29

Rajesh pose la question :
what is greater 1999¹⁹⁹⁷ or 1997¹⁹⁹⁹?
Chris Fisher lui répond.

Two log problems 2001-06-16

A student pose la question :
Hi..this is one of 9th grade student in Fort Worth TX. well..I am doing EPGY stuffs in my school right now..and.. me and my teacher had problems to solve some advanced logarithmic thing. so I searched some sites to solve these two questions

(log base 7 * 10) * (log base 10 * X ) = 2

log base 10 * (3x-4) + log base 12 * X
---------------------------------------------------
(log base 12 * 2) + (log base 12 * 5)

= log base 10 *4

Harley Weston lui répond.

An integration problem 2000-11-30

A student pose la question :
If a>0 and the integral from b to 0 of 1/(1+x) equals 1/2 the integral from a to 0 of 1/(1+x), express "b" in terms of "a"
Claude tardif lui répond.

Where will we use this in the real world? 2000-10-11

Jane Ann Musgrove pose la question :
As a teacher of mathematics, I am always asked "Where will we use this in the real world?". I am seeking ideas/sites via the internet where students can find answers to this type of question. Can you help me?
To be more specific, right now I am interested in finding careers where the employees would use the concepts of "Radicals", "Matrices", and "Logarithms". This information will be used by students to make presentations to the class on their findings from internet searches.

Harley Weston lui répond.

Isolating an exponent 2000-09-24

C. Scott pose la question :
Suppose you invest $500.00 in an account that pays 10% interest compounded annually. How long will it take for this value to triple?
A=p(1 + i)^a A=1500 i=0.1
1500=500(1.1)^a p=500 a=unknown
How do you solve this problem algebraicly? How do you isolate the variable (a) when it is an exponent?

Harley Weston lui répond.

Logs and trig functions 2000-09-12

Becky pose la question :
How do they get these answers?

log 8 + log 2 = ?
Answer is: log 16

For 0 degree < x < 90 degree, how many solutions are there for the equation 2sin x = cos x?
Answer: 1

Penny Nom lui répond.

LOG(LN(x)) = 1 2000-07-28

An algebra student pose la question :
LET F(x)=LOG X AND G(x)= LN X. SOLVE (f *G)(x)= 1
SHOW COMPOSITION AND USE DEFINITION OF LOGS.
Harley Weston lui répond.

An equation involving x to the x 2000-07-22

Joy Peter pose la question :
I am joy, a teacher teaching Maths at the secondary level and while solving a sum came to this stage when i got x^x (1 + log x) = 0, by which we can conclude that x^x = 0 or 1 + log x = 0. If x^x = 0, than what should be the value of x? I feel that the value of x should then be 0 (zero) but then how do I explain this to the students as we also know that anything to the power of 0 is 1 but here 0 raised to 0 is 1. If this is not defined then how do I explain this?
Penny Nom lui répond.

Radioactive decay 2000-05-18

Catherine Sullivan pose la question :
Please help me with the following: The radioactive isotope carbon-14 is present in small quantities in all life forms, and it is constantly replenished until the organism dies, after which it decays to carbon-12 at a rate proportional to the amount of C-14 present, with a half life of 5730 years. Suppose C(t) is the amount of C-14 at time t.

Find the value of the constant k in the differential equation: C'=-kC

In 1988 3 teams of scientists found that the Shroud of Turin, which was reputed to be the burial cloth of Jesus, contained 91% of the amount of C-14 contained in freshly made cloth of the same material. How old is the Shroud according to the data?

Harley Weston 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.

Logs 2000-04-12

Jessica pose la question :
Write as a single log 3ln x - 2ln(y+e) + 5ln(x-12) - 4ln y
Harley Weston lui répond.

Compounding continuously 2000-03-21

Gina pose la question :
You deposit $1500 in an account that pays 6.5% annual interest, compounded continuously. Find the balance after 10 years.
I'm not sure what to do with the "compounded continuously" part.

Penny Nom lui répond.

Characteristic of a logarithm 2000-03-14

Andrew Strauss pose la question :
What is the characteristic of log base 18 of 1980 ?
Harley Weston lui répond.

Logarithms 2000-01-18

Jennifer pose la question :
Hi I have a test tomorrow and I was wondering if you could help me with these two problems.

Explain how to express y in terms of x if log3y=4log3(2X)

The LN key on your scientific calculator is not working, but the ex and LOG keys are. Write directions for calculating a natural logarithm using the ex and LOG keys. Explain why these directions will get you the right answer.

Harley Weston lui répond.

Capacitor discharge rate 2000-01-09

Bill Phillips pose la question :
I need to be solve for t in the following rate problem for an electrical capacitor. Vr = E(e^-t/RC), e=nat. log 2.718 raised to the -t/RC power.
Harley Weston lui répond.

Logarithms 1999-12-16

Pierre pose la question :
Can you please answer those three question

inverse or the exponential function.
logx 81 = 4,
x expo4 = 81,
x = +or- 4square root 81,
x = +or- 3
s.s = {3}
Why is -3 not acceptable.

.
.
.

Harley Weston lui répond.

Log Cancel 1999-12-03

Justin Murray pose la question :
Ok I feel like a goof because I know this and I cant think of an answer But I want to isolate the x in the function y=2^x how do I do this?
Harley Weston lui répond.

Two derivatives 1999-11-16

Gina Renicker pose la question :
The derivative of:
y=e^(xlnx) and y=x^{2arctan(x^1/2)}
Harley Weston lui répond.

Area of a circle and an inequality 1999-10-30

Adam Anderson pose la question :
I have two problems.
The first: prove that the area of a cirlce is pi times radius squared without using calculus.
The second: show that ln(x) < x - 1 for all x > 0.

Harley Weston lui répond.

Derivatives with logs 1999-10-26

Kate pose la question :
What is the derivative of 5 to the 5x-2 at x equals 0.8?
Harley Weston lui répond.

-log(a) 1999-10-22

Brenda Miskimmin pose la question :
I need to know the mercury concentration in mg/L or ng/L for the following:
-log M (Hg) = 8.5
where mw of Hg=200.59
(it's the negative sign in front of log that confuses me).
Harley Weston lui répond.

Solving using logs 1999-10-11

Rich Bolton pose la question :
Here's my question:
$541.39(1+i)¹⁵=784.09
Can you please show me how to do this?
Penny Nom lui répond.

A log problem 1999-05-08

N. Lam pose la question :
I don't understand how to do this type of question:
log(base absolute value x)y = log(base abs.val.x)2 + log(base abs.val.x)(Cos x)
How do you graph the equation also, if -2(3.14)<=x<=2(3.14)
Harley Weston lui répond.

John Napier and e 1999-02-06

Shimin pose la question :
I would like to ask about the exact definition of e, its history (like how John Napier came about discovering it) and its applications in problems and real life situations. Thank you!
Chris Fisher lui répond.

Logs 1998-10-21

Benny pose la question :
What does log means? How come we have to use log
Chris Fisher lui répond.

Two Problems 1998-07-28

James Pulver pose la question :
How do you solve these problem? If log abc=16 and log ac=12 , find b. (The logs are log base 10.)
and
If a and b are real numbers, i^2 = -1 and (a+b)+5i=9+ai what is the value of b?
Jack LeSage lui répond.

A Problem with Logs. 1997-11-26

Herman pose la question :
Given log 24=a, log 25=b and log 26=c, express log 39 in terms of a, b and c.
Penny Nom lui répond.

Natural Logarithm Functions 1997-04-23

Rickson pose la question :
The following two questions are some of my son's homework that he is having trouble with......any advice or assistance would be appreciated.
(eX)5=1000.............the X and 5 are exponents
lnx + ln(x+3) = ln10
In each question the problem is to find x.
Harley Weston 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.