# Indefinite integral help

1. Jan 18, 2008

### uman

How can I evaluate $\int\frac{dx}{\sqrt{1-2x-x^2}}$ using inverse trig functions? Thanks.

2. Jan 18, 2008

### rock.freak667

complete the square of the quadratic.

3. Jan 18, 2008

### uman

Oh... thanks.

Dang these are so hard... I wish I had the creativity to see the solution immediately like that...

4. Jan 18, 2008

### rocomath

ax^2+bx+c, a=1, factor out the negative before you complete the square if you didn't remember.

5. Jan 18, 2008

### uman

Thanks. I got the right answer after rock.freak667's hint. I just wish I were able to solve these more easily, without hints from this forum and elsewhere.... does it just take lots of practice, or what?

6. Jan 18, 2008

### rocomath

Go here to see a variety of diff. methods.