# A simple integral?

1. Dec 9, 2007

### Mattofix

A simple integral?!?

1. The problem statement, all variables and given/known data

Integrate 1/(K+ x^2)^(3/2) dx

2. Relevant equations

3. The attempt at a solution

substitution of some kind - if it had an x on top it would be fine...

2. Dec 9, 2007

### arildno

Set $$x=\sqrt{K}Sinh(u)$$ and proceed.

3. Dec 9, 2007

### HallsofIvy

Staff Emeritus
arildno loves that hyperbolic substitution!

Myself, I would have immediately thought that "$tan^2(\theta)+ 1= sec^2(\theta)$" and used the substitution $x= \sqrt{K}tan(\theta)$. I suspect it is just a matter of taste.