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Approximations |
1999-12-20 |
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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. |
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Comma as decimal separator |
1999-12-18 |
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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. |
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Septante |
1999-12-18 |
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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. |
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The area of a garden |
1999-12-17 |
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Jessica Wells pose la question :
Hi My name is Jessica Wells and I am 10 years old. I was hoping you could help me out wityh a question my dad gave me. It is if aq graden is 32cm in diameter and I want to know the area of it what process do I use? He's a math wiz so I need o show him that I'm smart too
Penny Nom lui répond. |
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Two algebra problems |
1999-12-17 |
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Michael Standfest pose la question :
If x+4 is a factor of 2x4+kx3-3kx2+6x-40, find k and Prove that n2-n is even for all n, using the proof of contradiction
Penny Nom lui répond. |
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Proving a trigonometric identitiy |
1999-12-17 |
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Ryan pose la question :
I need to figure out how to prove that sec2x + csc2x = sec2x csc2x. I am not sure where to start out with it and whether I should use reciprocal, quotient, or pythagorean.
Penny Nom lui répond. |
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Logarithms |
1999-12-16 |
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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. - .
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Harley Weston lui répond. |
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Rectangular hyperbola |
1999-12-15 |
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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. |
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A decreasing ellipsoid |
1999-12-15 |
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A student instructor pose la question :
The volume of an ellipsoid whose semiaxes are of the lengths a,b,and c is 4/3 *pi*abc. Suppose semiaxes a is changing at a rate of A cm/s , the semiaxes b is changing at B cm/s and the semiaxes c is changing at C cm/s . If the volume of the ellipsoid is decreasing when a=b=c what can you say about A,B,C? Justify.
Harley Weston lui répond. |
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A model area |
1999-12-15 |
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John Ost pose la question :
Hello, I am a college student taking an elementary math course I need if possible assistance to developing an area model 36 x 25 that shows each of the four separate partial products. I must know how to do the computation 36x25 showing each of the four partial products separately, and indicate how each corresponds to the drawing that is required of the area model.
Penny Nom lui répond. |
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Cutting a carpet |
1999-12-15 |
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Heather pose la question :
A rectanglular piece of carpeting is 90 inches long and 90 inches wide. How can the carpet be cut into two pieces of equal sides and shape to cover an area of 100inches? There can only be one cut and no scraps. Please show me how.
Penny Nom lui répond. |
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.400 in Baseball |
1999-12-15 |
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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. |
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Fibonacci Numbers |
1999-12-15 |
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Gary Nelb pose la question :
I'm doing a project on fibonacci numbers and I'm using different starting values and finding out if different starting values to see whether or not the ratios still get closer to phi. I was wondering, what numbers should I use. Should I use two of the same # like 2 and 2, or numbers like 1 and 2, or even something totally different.
Denis Hanson lui répond. |
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Two calculus problems |
1999-12-13 |
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Alan pose la question :
I have 2 questions that are very new to me, they were included on a quiz and the material was never covered. Our teacher never explained the purpose and detailed explanation of how to solve the problem. Could you help? Thanks. Question 1:
A ball is falling 30 feet from a light that is 50 feet high. After 1 sec. How fast is the shadow of the ball moving towards the light post. Note that a ball moves according to the formula S=16t^2 Question 2:
How many trapezoids must one use in order for the error to be less than 10^-8 if we want to find the area under the curve Y=1/X from 1 to 2. Find the exact area, Graph the function and use the trap rule for the "N" that you found.
Harley Weston lui répond. |
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Passing trains |
1999-12-10 |
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Nancy pose la question :
Two trains, each of 80 cars, must pass on a single track which has a deadend siding. How can they pass if the siding can only hold a locomotive and 40 cars? I do not understand this...help. It will be due monday. I thought it would be simple if the siding could hold 80 cars.
Penny Nom lui répond. |
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