Centrale des maths - centraledesmaths.uregina.ca
Dilemmes & doutes
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 calcul des hh,mn,sec 2008-01-19 gillot pose la question :bonjour, mon fils à des additions et soustractions d'horaire et je n'arrive pas à trouver la règle pour lui espliquer comment il faut faire il y a t il une formule pour les additions et soustractions merci par avance pour vos réponsesClaude Tardif lui répond. A=B+C+D+F+G+H+J 2007-11-27 Boubendir pose la question :voila ma question et comme savoir les nombres additioné en etulisant le resultat A=B+C+D+F+G+H+J au debut ons a les B,C,D,F,G,H,J on connaissent leur valeur comment retrouver valeur on etulisant leur resultatClaude Tardif 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. Adding two negatives 2018-02-04 Pinasshakoane pose la question :(-23)+(-3)Penny Nom lui répond. Adding fractions 2017-10-27 Sandy pose la question :virinchi distributed 4/7 of cake to his friends 1/3 of it to his family members which part of cake is remaining?Penny Nom lui répond. Multiplication and repeated addition 2016-11-23 Anandmay pose la question :Hello I was looking closely at early arithmetic where I found how we discovered properties of Arithmetic. Like:2 x 3 = 3 x 2. This can be proved by considering a 2-D figure(actually,quadrilateral) having length consisting of 2 boxes of 1-by-1 dimensions and breadth of 3 boxes of the same dimensions. Now,consider it again,but,this time,length of 3,and breadth of 2 of such 1 by 1 boxes. We now notice that we can fit the 2 types of rectangles formed on each other precisely. So the multiplicative property of commutativity is true for all natural numbers as we can generalize the result(in our mind,for self satisfaction). Now,can you find me a nice satisfactory reason of why a fraction times a natural number equals the number times the fraction? I mean, for example,i can understand the meaning of 3 x 2/3 to be three times 2-3rd,that is, 2/3+2/3+2/3.Fair enough. But here is the problem:By definition and actual meaning of multiplication, a x b means the repeated sum of b,done 'a' times. So what is the meaning of doing 2/3 x 3?The repeated addition of 3 how many times??2/3 times??Not making sense,right?And even we have not proved yet the commutative property of numbers INCLUDING fractions.So how can we resolve this problem and make these things meaningful? ThanksPenny Nom lui répond. find f+g 2016-06-26 yzabelle pose la question :find f+g f(x)=x^2-1 g(x)=square root of x+2Penny Nom lui répond. Fractions of two quantities 2016-01-22 Melody pose la question :Kate ate 1/4 of her orange. Ben ate 2/4 of his banana. Did Kate and Ben eat 3/4 of theit fruit? Explain.Penny Nom lui répond. Complex numbers in standard form 2016-01-15 Michael pose la question :express the following complex numbers in standard form (2+3i)+(5-2i)Penny Nom lui répond. A ladder against a wall 2014-07-09 thabo pose la question :A ladder 6.5m long,leans against a wall so that the top of the ladder is 4.8m from the ground.what is the angle of elevation of the ladder to the top of the wallPenny Nom lui répond. Adding fractions 2014-01-31 bianco pose la question :2/3+3/4= 9/8-6/8=Penny Nom lui répond. A word problem involving fractions 2014-01-23 Pamela pose la question :John put 1/4 of his flowers in a vase He gave 1/2 to of the flower to his wife He gave 1/5 of the flowers to his daughter He has 8 flowers left How many flowers did John start withPenny Nom lui répond. Why can't we add or subtract speed? 2013-11-21 kashish pose la question :why we cannot add or subtract "speed" / directly in any given distance , speed , time questions?Chris Fisher lui répond. Adding mixed numbers 2013-11-20 Kathy pose la question :1 3/4 + 1 2/3= ? 5 1/2 - 2 5/6= ?Penny Nom lui répond. Group the addends so that you can add mentally 2013-10-01 monica pose la question :the questions in the homework says change the order or group the addends so that you can add mentally ,find the sum and tell which property you used 120+37+280 and 25+25+30Penny Nom lui répond. Ann has a bag of marbles. 2013-07-25 Carmen pose la question :Ann has a bag of marbles. she gave one half to her friend Tina and then one third to her friend Tom. Now left with 15. How many did she had originally?Robert Dawson and Penny Nom lui répond. Cutting three sections of pipe 2013-05-16 Michael pose la question :A plumber cuts three sections of pipe from a 12’ length of ABS pipe, the lengths of the sections are 33 3/8”, 56 5/8” and 39 7/8”. What is left over from the full length, if the saw cut is 1/8” wide?Penny Nom lui répond. Adding two fractions 2012-09-19 jeanette pose la question :Question from jeanette, a parent: can you help me figure this according to BEDMAS I am lost steps please: $\frac{12.75^2}{50} + \frac{13.49^2}{60}$ I hope this is not too confusing for you it is to me...Harley Weston lui répond. Adding more than 2 fractions 2012-09-10 Anonymous pose la question :How do you add or subtract more than 2 integer fractions? OK, here is an example. -5/6 + 7/4 + 13/8 Please tell me the steps. Thanks- grade 9 studentRobert Dawson and Penny Nom lui répond. Adding speeds 2012-08-26 Roy pose la question :May I ask if it is correct to add the following with units included? Some tell me that the units cannot be included in the addition because we cannot add speed.Harley Weston lui répond. Adding fractions 2012-01-05 laurie pose la question :if shaded parts of a circle are 4/7 and the other is 1/3 what fraction is leftPenny Nom lui répond. 1 third plus 5 sixths 2011-11-10 Matt pose la question :1 third plus 5 sixths =Penny Nom lui répond. pi/2 + 12/13 2011-05-24 Jen pose la question :If you have (pi/2) and you want to add it to (12/13), how would you go about it?Chris Fisher lui répond. Multiplication and order 2011-01-21 Janet pose la question :IN A MULTIPLICATION SENTENCE BASED ON A DRAWING..IS THERE ANY ORDER FOR THE MULTIPLICAND ANG MULTIPLIER FOR THE ANSWER TO RIGHT?Robert Dawson lui répond. 1/a^2 + 1/b^2 2011-01-19 robert pose la question :If (a + b)^2 = 81 and ab = 18, find the value of 1/a^2 + 1/b^2 ?Penny Nom lui répond. Convert to multiplication 2010-10-23 angelina pose la question :how to covert 5+5+5=15 to multiplicationPenny Nom lui répond. 4.5 PLUS 29 2010-09-07 kiona pose la question :4.5 PLUS 29Penny Nom lui répond. A ladder against a wall 2010-03-25 amber pose la question :the distance from the bottom of the ladder to the building is18 foot less than the length of the ladder.How high up the building is the top of the ladder if that distance is 1 ft less than the length of the ladder?Penny Nom lui répond. A 6m ladder is placed against a wall 2010-03-09 Trevor pose la question :A 6m ladder is placed against a wall making a 56 degree angle with the ground. How far up the wall does the ladder reach?Harley Weston lui répond. A 25 foot ladder reaches a window 20 feet high 2010-02-27 Tanner pose la question :a 25 foot ladder reaches a window 20 feet high. how far is the ladder from the building? how far must the foot of the ladder be moved to lower the top of the ladder by four feet?Tyler Wood lui répond. Least common denominator 2010-02-13 Priscila pose la question :3/8 + 4/5 + 7/3 + 9/10 = ? Thank you for your assistance. PriscilaPenny Nom lui répond. Combining fractions 2010-02-10 Nick pose la question :Combine the fractions 2m/t + 5/mtPenny Nom lui répond. Ladder Leaning on a Wall 2009-05-14 clinton pose la question :a ladder rests against a wall 24m high.the foot of the ladder is 7m from the foot of the wall. How do you calculate the length of the ladderRobert Dawson lui répond. A ladder against a wall 2009-04-08 Jessica pose la question :The angle of elevation of a 15 ft. ladder is 70 degrees, find out how far the base of the ladder if from the wall.Penny Nom lui répond. A five game average of 148 2009-04-01 Shelly pose la question :(128 + 145 + 139 + 157 + x) divided by 5 = 148 matches the situation stated below: A person bowled four games and scored 128, 145, 139, and 157. Find x, the score the person would need to have in the fifth game to average 148 for all five games. How do I solve this and how am I supposed to add x like it says in the equation?Penny Nom lui répond. The length of a ladder 2009-03-30 Susan pose la question :The foot of an extension ladder is 7 ft. from a wall. The height that the ladder reaches on the wall and the length of the ladder are consecutive integers. How long is the ladder?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. Multiplying in different bases 2009-02-25 Susan pose la question :11 base 2 X 22 base 3 + 33 base 4 = _________ base 5Robert Dawson lui répond. Averaging percentages 2009-02-21 Chris pose la question :Ok I'll give you a simple example of what I'm doing. Lets say that on one forum, a memebr has made 52 posts out of the 412 posts made altogether. Then on another forum, the same person has made 10 posts out of the 60 posts altogether. What percentage of the posts has this person made in these 2 fourms combined.Robert Dawson and Harley Weston lui répond. Adding fractions 2008-09-17 amanpreet pose la question :please can you help me to simplify: 2(c-3) / 7 + 3(4c-2)/2Penny Nom lui répond. Three addends that sum to ten 2008-09-13 Alfred pose la question :How many probabilities are there to have 3 addends to get a sum of 10? What is the formula?Harley Weston lui répond. Grouping addends 2008-09-13 juan pose la question :how do you group the addends then find the sum: 2+4+6=Penny Nom lui répond. How far is the ladder from the wall? 2008-07-10 Al pose la question :a ladder is leaning against a wall at a 70 degree angle and the ladder is 20 feet tall...how far away is the ladder from the wallPenny Nom lui répond. .9 repeating plus .2 repeating 2008-06-10 megan pose la question :How do you express the addition of .9 repeating plus .2 repeating?Penny Nom lui répond. How do you add decimals? 2008-06-05 nyheashiacurry pose la question :how do you add up decimals?Janice Cotcher lui répond. 3 radical 48 +11 radical 75 2008-05-24 Maria pose la question :Add 3 radical 48 +11 radical 75. Write answer in simpliest form.Penny Nom lui répond. Adding rational functions 2008-04-29 Jonathon pose la question :1/(x+3) + 1/(x^2+5x+6) =Penny Nom 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. Sum and difference of cubes 2008-01-30 Amanda pose la question :It has been a really long time since I was in Algebra and I can't remember how to factor cubes such as x^3 +81 or subtracting/adding fractions with variables such as [1/(x+h)+2]-[1/x+2]. Please help!!!Penny Nom lui répond. Adding fractions 2007-12-31 Lisa pose la question :As an educator in Adult Education, I am preparing a young man for a US Government test. The equation I have trouble with is explaining the following equation. It asks: If it takes A 3 days to dig a certain ditch, whereas b can dig it in 6 days, and C in 12, how long would it take all three to do the job? I know the equation is 1/3 + 1/6 + 1/12 and it equals = 7/12 but I don't understand how it equals 7/12. This simple math eludes me. So the question is not the final answer of 1 and 5/7 of days but where one comes up with the 7/12?Penny Nom and Claude Tardif 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. Addends 2007-11-27 jessica pose la question :what is a addends my son needs to write a number sentence that has two addends that are the sameStephen La Rocque 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 helpHarley Weston lui répond. Adding algebraic fractions 2007-08-14 John pose la question :Ive completely forgot anything to do with the subject mentioned, so my question is straight to the point.. I need to know how to do the following problem (Preferably do not give me an answer though) (k/3k-8) - (4/k+2)Penny Nom lui répond. Fractions of fractions 2007-07-18 Bridget pose la question :Sam and Mary each owned one-half stock in a printing company. Sam sold 2/3 of his stock to Mary. What fractional part of the printing business does Mary now own?Penny Nom lui répond. Period of a sum of trig functions 2007-06-17 Aakash pose la question :the period of the function f(x)=cos3x+sin4x+tan4xStephen La Rocque lui répond. How high does the ladder reach? 2007-06-11 Madi pose la question :A ladder 8 ft long resting on a house makes a 60 degree angle with the ground. how far up the house does it reach?Stephen La Rocque lui répond. Linear systems 2006-09-21 Alexander pose la question :Hello, i have a math assignment due tonight at midnight and i need some help please It is using the addition method to solve linear systemsPenny lui répond. 1/x + 1/y 2006-08-11 Sonya pose la question :what is 1/x+1/y = ? is it equal to 1/x+y or what?Penny Nom lui répond. Rate of ladder falling 2006-04-30 Harsh pose la question :A ladder 4 m long rests against a vertical wall. If the bottom of the ladder slides away from the wall at a speed of 30 cm/s, how quickly is the top of the ladder sliding down the wall when the bottom of the ladder is 2 m from the wall?Stephen La Rocque lui répond. Adding polynomials and counting the terms 2006-04-28 Kris pose la question :Suppose that two polynomials, each containing 3 terms, are added. Is it possible for the sum to contain more than 3 terms? fewer than 3 terms? exactly 3 terms? Explain.Leeanne Boehm and Steve La Rocque lui répond. Ladder and wall 2006-04-27 Lori pose la question :A 12-foot ladder is leaning across a fence and is touching a higher wall located 3 feet behind the fence. The ladder makes an angle of 60 degrees with the ground. Find the distance from the base of the ladder to the bottom of the fence.Stephen La Rocque 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. Adding with mixed fractions 2006-03-30 Becca pose la question :can anyone help with how we change to get the same denominator with adding whole number. example:8+7 3/8 6 1/2 + 2 5/6 Stephen La Rocque lui répond. Adding fractions 2006-03-26 Barbara pose la question :I know that to subtract 1/4 from 2/3 I must find a common denom. Now the 2/3 becomes 8/12.....i understand the 12, but where does the 8 come from?Penny Nom lui répond. A 25 foot ladder is leaning against a building. 2006-03-24 Ali pose la question :A 25 foot ladder is leaning against a building. The base of the ladder is 7 feet from the building. How high up the building does the ladder reach? Stephen La Rocque lui répond. Daddy Warbucks' cash 2006-02-22 Grace pose la question :Daddy Warbucks always carries a specific number of $100 and$500 bills for impulse purchases and $1 bills for tips. If he has 500 bills in his briefcase and they total$50,000, how many bills of each denomination does he carry?Stephen La Rocque lui répond. GCF, LCM, primes and the ladder method 2006-01-07 Linda pose la question :How would I teach both finding the GCF and LCM with prime factors...I recall the ladder method vaguely.???Penny Nom lui répond. Adding 10 and multiples of tens to one and two digit numbers 2005-12-13 Meghan pose la question :I am teaching in a grade 2/3 class and I am struggling with trying to find a simple way of explaining to the students how to add 10 and multiples of tens to one and two digit numbers.Diane Hanson lui répond. Adding improper fractions 2005-11-25 Paula pose la question :I would like a simple step by step explanation on how to add improper fractions.Penny Nom lui répond. How to add three addends 2005-09-28 Patricia pose la question :explaination of how to add three addends if you use a double to add or if you use a sum of 10 8+3+2= 6+4+0= 3+3+6= 2+5+4= Baul Betts and Penny Nom lui répond. The language of subtraction 2005-09-26 Chris pose la question :When you have an addition problem you have two addends that equal a sum. Therefore . . . I know the answer to a subtraction problem is the difference - what is the name of the numbers that make up a subtraction problem?Diane Hanson and Harley Weston lui répond. Adding positive and negative numbers 2005-09-03 Billy pose la question :46 + -24 = -38 + -22 = 19 - 20 = 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+5Penny Nom lui répond. The least common denominator 2004-11-03 A student pose la question :Write the LCD for each pair of fractions. 13. 1/3,1/5 14. 2/7,1/4 15. 3/4,3/5Penny Nom lui répond. Subtracting fractions 2004-05-11 Filipe pose la question : Question: _5_ - __7__ 6ab 8aPenny Nom lui répond. A/30 + B/105 = (7A + 2B)/x 2004-02-05 Jim pose la question :If A/30 + B/105 = (7A + 2B)/x and A, B, and x are integers greater than 1, what must x equal? Penny Nom lui répond. Adding percentages 2003-12-19 Paula pose la question :How do you add percentages e.g 90% + 80% + 60% + 54% + 25% = ? Penny Nom lui répond. Adding fractions 2003-11-16 Ken pose la question :My name is Ken and I am taking my GED course for my High School and have not been in a class for 35 years. I am doing this for re-training. I am at the part about fractions. Here is an example that I am having trouble with. 1 3/7 + 4 2/3 + 11/21 They have no common denominators. Could you PLEASE help me. If you could send me a step by step explanation it would be greatly appreciated.Penny Nom lui répond. A 16 foot ladder 2003-09-04 Kelly pose la question :Two buildings are separated by a three-foot alleyway. Fatima wants to use a 16 foot ladder to reach a window in the wall of one of these buildings. If she places the foot of the ladder against the base of the other building, how far up the wall will the top of the ladder reach??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. Common Denominator 2002-08-26 Slobodanka pose la question :What is a Common Denominator?Penny Nom lui répond. Adding algebraic fractions 2002-03-20 Dolores pose la question :I get totally confused with this problem. I get confused with the getting the lowest terms. 4/x-5 + -2/x -10/x^2-5x Penny Nom lui répond. F = -3 + 3 2002-03-19 Jessica pose la question :F= -3 + 3 WHAT IS F?????Penny Nom lui répond. Adding algebraic fractions 2002-01-23 Francine pose la question : Hello, I've come up with an answer for the following problem but it's not the same as the book's answer. However, the book has a lot of mistakes in it and I don't know if I'm doing it properly or not. Your help would be soooo appreciated. It's driving me crazy.The problem is: 2 + 3 + 4 --------- + --------- + ---------- (x-1)^3 (x-1)^2 (x-1) [(x-1)^3 is (x-1) to power of 3 etc.] Penny Nom lui répond. Adding vectors 2002-01-12 Lena pose la question :how do you add vectors together? If you are given the length and angles of both vectors and are asked to add/subtract them, how do you do it? I know you are supposed to do the head to tail method, but whenever i try it i get the wrong answer. I need help setting it up. example: A is 2.7cm, and 60 degrees, B is 1.6cm and 135 degrees, find the magnitude and amplitude Penny Nom lui répond. Odd plus even is odd 2001-10-14 James pose la question :Why is the sum of an odd number and an even number always odd?Peny Nom lui répond. Adding and subtracting rational expressions 2001-05-03 Donna pose la question :Adding and subtracting Rational expressions. I am in grade 10 and I am a student here is an example of the questions: 1/(x+1) - 1/(x-1) = ? Penny Nom lui répond. Adding functions 2001-02-19 Jackie pose la question :f(x) = x2 + 1; g(x) = x2 - 1 find a) ((f+g) of h)) (x) b) ((f-g) of h)) (x) c) ((f of h) - (g of h)) (x) Penny Nom lui répond. What is wrong with these probelms? 2001-02-09 Cindy pose la question :Hi, I am a planning on becomming a teacher and i am asked to find out what is wrong with these probelms and how i would go about showing a student what is wrong with them!! Error in patterns: 13/35=1/5; 27/73=2/3; 16/64=1/4 4/5+2/3=6/8; 2/5+3/4=5/9; 7/8+1/3=8/11 2/3*3=6/9; 1/4*6=6/24; 4/5*2=8/10 Leeanne Boehm and Penny Nom lui répond. Order of operations 2000-11-26 Margaret Pratt pose la question :My daughter has a math question and I am afraid I am of no help. Can you help? 2x5/2+1-5= She arrives at 8 as the answer and has been told this is incorrect. Any help you can give would be appreciated.Penny Nom lui répond. Word addition 2000-07-05 Harman Chaudhry pose la question :What is the value of DISHES if SEE + THE + WAITER + WASHES = DISHES. In addition, I know there is a name for these types of problems--what are they actually called?Chris Fisher lui répond. Why does division start from the left? 2000-05-24 Salil Dave pose la question :Addition, subtraction and multiplications start with right most digit and proceed left, but division starts from left-most digits and goes right ... why? Harley Weston lui répond. Adding fractions 2000-04-23 A grade 6 student pose la question :In adding fractions, how do I rewrite the fractions so that the denominators are equal? The problem is 3/4 + 1/6 = The other problem is 11/18 + 4/9 =Penny Nom lui répond. Making fruit salad 2000-03-29 A grade 5 student pose la question :Miss.Muffet males a fruit salad by adding 31/2 pounds of grapes and 4 1/4 pounds of apples to every 2 1/4 pounds of melon. How many pounds of grapes does she use in 50 pounds of fruit salad? Claude Tardif lui répond. Addition 2000-01-11 Deanna pose la question :what is the answer for 20+5+32-3+98Penny Nom lui répond. The shortest ladder 1999-06-26 Nicholas pose la question :A vertical wall, 2.7m high, runs parallel to the wall of a house and is at a horizontal distance of 6.4m from the house. An extending ladder is placed to rest on the top B of the wall with one end C against the house and the other end, A, resting on horizontal ground. The points A, B, and C are in a vertical plane at right angles to the wall and the ladder makes an angle@, where 0<@Harley Weston lui répond. A ladder problem 1999-04-22 Michael Blade pose la question :There is a cube box 3feet x 3feet x 3ft resting against a vertical wall on level ground. Resting against the outside corner of the box is a ladder 10 feet tall, this ladder is of course resting on the ground but also against the outside corner of the box and rests on the wall. The question- the ladder is divided into two unequal section bounded by the box to the ground and the box to the wall. what are those dimensions?Penny Nom lui répond. A number between 1998-11-25 Jimmy Nikola pose la question :A number is less than 3,425 + 8,630 and greater than 7,614 + 4,429. What could the number be? This question is on page 93, question number 23. in Silver Burdett Ginn Math book, which is a 3rd grade math book.Jack LeSage lui répond. Adding Fractions 1998-10-15 Lindsay pose la question :please help me!!!!Harley Weston lui répond. A Sum or Product of Fractions 1998-10-06 Emily Robb pose la question :Find a pair of fractions that when they are multiplyed and added the sum /product is the samePenny Nom lui répond. Adding Fractions 1998-10-03 Pam Bailey pose la question :Can you help me simplfy this? (1/2a + 1/3b) - (1/4a - 1/5b) + (1/6a - 1/7) thanxHarley Weston lui répond. Using your fingers 1998-04-21 Ian Sutherland pose la question :My 7-year-old son, in Grade 2, constantly uses his fingers to count.  I know for now this is a useful crutch but at what point should he stop? Diane Hanson lui répond.