# What is the integral of xe^-x?

1. ### Grimertop90

1
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. ### quasar987

4,770
Try integration by parts.

3. ### HallsofIvy

40,678
Staff Emeritus
Let u= x, dv= e-xdx.

4. ### Count Iblis

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