 |
|
|
|
|
|
|
|
|
Approximations |
1999-12-20 |
|
From Adrian Valc:
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?
Answered by Chris Fisher. |
|
|
|
|
|
|
Comma as decimal separator |
1999-12-18 |
|
From Franck Menuge:
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?
Answered by Patrick Maidorn and Penny Nom. |
|
|
|
|
|
|
Septante |
1999-12-18 |
|
From Guillaume Bessis:
Pourqoui et depuis quand en France emploie-t-on l'expression 'soixante-dix' et non septante pour désigner 70 ? (idem pour 90 et nonante)
Answered by Claude Tardif. |
|
|
|
|
|
|
The area of a garden |
1999-12-17 |
|
From Jessica Wells:
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
Answered by Penny Nom. |
|
|
|
|
|
|
Two algebra problems |
1999-12-17 |
|
From Michael Standfest:
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
Answered by Penny Nom. |
|
|
|
|
|
|
Proving a trigonometric identitiy |
1999-12-17 |
|
From Ryan:
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.
Answered by Penny Nom. |
|
|
|
|
|
|
Logarithms |
1999-12-16 |
|
From Pierre:
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. - .
.
.
Answered by Harley Weston. |
|
|
|
|
|
|
Rectangular hyperbola |
1999-12-15 |
|
From Aarti Chand:
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?
Answered by Chris Fisher. |
|
|
|
|
|
|
A decreasing ellipsoid |
1999-12-15 |
|
From A student instructor:
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.
Answered by Harley Weston. |
|
|
|
|
|
|
A model area |
1999-12-15 |
|
From John Ost:
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.
Answered by Penny Nom. |
|
|
|
|
|
|
Cutting a carpet |
1999-12-15 |
|
From Heather:
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.
Answered by Penny Nom. |
|
|
|
|
|
|
.400 in Baseball |
1999-12-15 |
|
From Nieve Nielson:
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?
Answered by Chris Fisher. |
|
|
|
|
|
|
Fibonacci Numbers |
1999-12-15 |
|
From Gary Nelb:
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.
Answered by Denis Hanson. |
|
|
|
|
|
|
Two calculus problems |
1999-12-13 |
|
From Alan:
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.
Answered by Harley Weston. |
|
|
|
|
|
|
Passing trains |
1999-12-10 |
|
From Nancy:
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.
Answered by Penny Nom. |
|
|
