## anonymous 5 years ago Integral of (lnx) / x ^ 2 from 1 to 2

1. anonymous

I couldn't find my original post so I had to repost it :/

2. anonymous

integrate by parts

3. anonymous

I know that but how!?

4. anonymous

choose f and dg so that the integral df g will solve easily

5. anonymous

let f be lnx and dg be 1/x^2

6. anonymous

df = dx/x and g= -1/x

7. anonymous

$\int\limits_{}^{}fdg = fg - \int\limits_{}^{}gdf$

8. anonymous

But I end up taking the integral of a natural log... don't i?

9. anonymous

no, you end up taking the derivative of it

10. anonymous

Oh you used the opposite for f and dg... ok that works