# Integrate Sqrt[x^2-a]

1. Dec 4, 2008

### coverband

Could someone show me how to integrate this. Bear in mind 'a' could be positive or negative thus i don't think we can use sqrt(a) in our answer...

2. Dec 4, 2008

### rock.freak667

But for a<0 => -a>0 meaning that your integrand will become sqrt{x^2+b} where b=-a

3. Dec 4, 2008

### B-Rye

Shouldn't matter if it's positive or negative, the integral is still the same, imaginary or not.

4. Dec 4, 2008

### mathwonk

use trig substitutions, sec or tan depending on whether a is positive or negative.

5. Dec 5, 2008

### coverband

only problem is say if I use the substitution Let x = sqrt(a)Secy the integrated result has a tany in it