# Math Help - Integration by parts

1. ## Integration by parts

I'm trying to learn integration by parts and I feel as though I have a grasp on the formula, however the back of the book's answers are disagreeing with mine. I searched online for something to help teach me how to do this kind of integration and came upon this: http://www.math.umn.edu/~rosenfie/c/...n_by_parts.pdf
It seemed it would be helpful, but I'm stumped on how they get some of their answers. When they integrate (x^2)(e^x), on page 2 of 3, they some how end up with (x^2)(e^x)-the integral of 2xe^2dx. Where is the e^2 coming from?

2. Hello,
Originally Posted by HellaciousD
I'm trying to learn integration by parts and I feel as though I have a grasp on the formula, however the back of the book's answers are disagreeing with mine. I searched online for something to help teach me how to do this kind of integration and came upon this: http://www.math.umn.edu/~rosenfie/c/...n_by_parts.pdf
It seemed it would be helpful, but I'm stumped on how they get some of their answers. When they integrate (x^2)(e^x), on page 2 of 3, they some how end up with (x^2)(e^x)-the integral of 2xe^2dx. Where is the e^2 coming from?
It is a typo
You can see in the following equality that they go back to the correct thing :

$\dots -2 \int xe^x ~dx$

3. Thanks, I swear many forces are conspiring against me to prohibit my learning of calc 2.