Hey guys,

I've got this problem in my exam that seems to come up a lot, I'm really stuck on where to go next.

$\displaystyle \int \frac {r^2 dr}{(a^2+r^2)^{3/2}}$,

I thought about substitution and integration by parts but can't figure out a way to make the r's cancel out.

If anyone has some advice on how to start this it would be greatly apreciated!

Thanks