What is the integral of xe^-x?

1. Sep 10, 2008

Grimertop90

I feel really dumb for not remembering this.... I'm drawing a total blank as to the antiderivative of xe-x or how to find it. Do I need to use a u substitution?

2. Sep 10, 2008

quasar987

Try integration by parts.

3. Sep 10, 2008

HallsofIvy

Staff Emeritus
Let u= x, dv= e-xdx.

4. Sep 11, 2008

Count Iblis

You can also compute the intergal of exp(-a x) and then differentiate w.r.t. the parameter a.