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11 items are filed under this topic.
Partitions into distinct parts 2015-09-19
From Brian:
Looking for a formula where I can type in a number, 17 for example, and using the numbers 1 through 17 (1, 2, 3, 4 etc....), to come up with all possible combinations, when added, that will equal 17. And each number can only be used once. I've tried a few search engines but my computer stares at me blankly and scratches its head :-/.
Answered by Chris Fisher.
The integral of sqrt(x) * ln(x) 2009-10-12
From Oana:
Hi! Can you tell me please how much is : ∫ (√x * ln x) ?
Answered by Penny Nom.
Integration 2008-10-17
From hazela:
integration of

x sinx cosnx

Answered by Harley Weston.
Integration by parts 2008-01-30
From seth:
hi i really dont understand integr ation by parts. for example, the integral(t^2sintdt. i have u=t^2 and v'=sint also u'=t^/3 v=-cost for the formula i have uv-integralvu' dx this is all well and good but i cant get it right.
Answered by Harley Weston.
Integration 2007-02-02
From Jenna:
How do I integrate ( ln(x) ) / ( x^2 ) ?
Answered by Penny Nom and Claude Tardif.
Can one divide a circle into 4.5 parts 2006-03-30
From Chris:
If it is possible, can one divide a circle into say, 4.5 parts (with 4 equal parts and a half part)?
Or for that matter, for any integer, n, into n/2 parts as above?]

Answered by Walter Whiteley.
Integrating e^x sin(x) 2003-05-03
From Lech:
I am having trouble integrating the following expression by parts:

ex sin(x)

I used the integrator at http://www.integrals.com/ to find the solution,

? 1/2 ex cos(x) + 1/2 ex sin(x).

This is easy to confirm by differentiation, however I am confounded as how to arrive at the answer.

Answered by Penny Nom and Claude Tardif.
Dividing a circle 2001-10-17
From Ahmeen:
I am having a hard time figuring out how a circle can be divided into 11 equal parts with only 4 cut allowed? My teacher gave this to us and I still can't cut my pie into eleven equal parts with only four cuts.
Answered by Walter Whiteley.
Integration by parts 2001-04-09
From A student:
how do you integrate x tan-1x dx, i know it can be done by integration by parts maybe, but i'm not sure....
Answered by Claude Tardif and Harley Weston.
Two integrals 2001-04-03
From Jim:
I'm having trouble with these integrals. Can you help me out?

1)the integral of:

x5 arctan x dx

2)the integral of:

2x5 + 9x4 + 19x3 + 13x2 - 5x - 25
----------------------------------------------- dx
x4 + 4x3 + 5x2

Answered by Claude Tardif.
Congruent parts of congruent figures 2000-03-10
From Erica:
Yesterday, I recieved a test problem asking to prove two line segments equal. Here is the problem as I was given it:

Given: paralleogram ABCD
AE is perpendicular to DB
CF is perpendicular to DB
Prove: AE is equal to CF

I answered the problem as follows:
Answered by Walter Whiteley.




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