# Homework Help: Bounded integral

1. Feb 7, 2009

### Swerting

1. The problem statement, all variables and given/known data
I have to take an integral of $$x^3/(1+x^2)$$ from zero to 1.48766439....(I have the number).

2. Relevant equations
None really.

3. The attempt at a solution
Well, I tried and tried, and I could not find a single way to seperate the top from the bottom. Also, I tried u substitution of both $$x^3$$ and $$1+x^2$$ but it never seemed to work out. I'm not sure if this would be good for integration of parts, since I believe that one must be able to be integrated multiple times, such as $$e^x$$, so any nudge in the right direction would help. I have the correct answer, I just would like to be able to know how to get to it. Thank you for your time.

-Swerting

Last edited: Feb 7, 2009
2. Feb 7, 2009

### Dick

Try writing it as x^2*x/(1+x^2). Now substitute u=1+x^2. Replace the x^2 in the numerator by u-1. Do you see it now?

3. Feb 7, 2009

### Swerting

Ah yes! I completely forgot about that! Thank you very much, I do believe I have it now!