# Homework Help: Integral question

1. Jan 25, 2009

### insynC

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

Trying to evaluate the following integral:

∫dx/(x√(x² - a²))

3. The attempt at a solution

I think I'm missing something simple. I know:

∫dx/(x√(x² + a²)) = - 1/a arccsch|u/a| + C

&

∫dx/(x√(a² - x²)) = - 1/a arcsech(u/a) + C

But I'm not exactly sure how to manipulate my integral into one of these forms.

Any suggestions? Thanks

2. Jan 25, 2009

### The Dagda

$$\frac{1}{x(x^2-a^2)^{\frac{1}{2}}}$$

Does that help?

3. Jan 25, 2009

### jgens

Let x = au, then dx = adu. Can you take it from there?

4. Jan 25, 2009

### insynC

It's just a standard integral for arcsec... :S don't know how I missed that.

Thanks for the help