# Indefinite integrals

• Feb 10th 2009, 07:45 PM
OpaqueCheshire
Indefinite integrals
I have a couple problems due tomorrow where you take r'(t) to solve for r(t) using r(0), but I'm having difficulty solving a portion of the problem. Concept-wise I'm asking with help finding the indefinite integral of t*e^t with respect to t. It's likely something simple that I overlooking, but I'd appreciate the help.
• Feb 10th 2009, 07:50 PM
Jhevon
Quote:

Originally Posted by OpaqueCheshire
I have a couple problems due tomorrow where you take r'(t) to solve for r(t) using r(0), but I'm having difficulty solving a portion of the problem.

we can't help you if you don't post what you're having problems with

Quote:

Concept-wise I'm asking with help finding the indefinite integral of t*e^t with respect to t. It's likely something simple that I overlooking, but I'd appreciate the help.
for $\displaystyle \int t e^t~dt$, the conventional way is to use integration by parts. recall the formula: $\displaystyle \int u ~dv = uv - \int v~du$

here, let $\displaystyle u = t$ and $\displaystyle dv = e^t~dt$
• Feb 10th 2009, 07:52 PM
OpaqueCheshire
Thank you. I knew there was something I was forgetting.