# Math Help - area between curves w/ integration by parts

1. ## area between curves w/ integration by parts

so the two curves are: 12ln(x) and xln(x) I got the bounds to be 1 and 12

so i got the integral between 1 and 12 of 12ln(x)-xln(x) dx. What do I do after this?

2. That's it, that's the answer

3. Originally Posted by krnbluemonkey
so the two curves are: 12ln(x) and xln(x) I got the bounds to be 1 and 12

so i got the integral between 1 and 12 of 12ln(x)-xln(x) dx. What do I do after this?
$12\ln{x} - x\ln{x} = \ln{x}(12-x)$

$\int \ln{x}(12-x) \, dx$

let $u = \ln{x}$ and $dv = (12-x) \, dx$

you know the rest ...

$\int u \, dv = uv - \int v \, du$