# Integrating by parts

## Homework Statement

∫r^3/(4+r^2)^(1/2) dr

∫udv=uv-∫vdu

## The Attempt at a Solution

I know that integration by parts must be used. I tried doing it with 4+r^2 as u, but kept running into issues..then I got an answer but it appears to be wrong. I guess I am not sure how to do this.

ehild
Homework Helper
First substitute r^2=t, then integrate by parts.

ehild

Dick
The substitution $u=r^2$ would be significantly easier to deal with. One can then use parts or another substitution to make the integral elementary.