How Do You Find the Integral of xe^-x?

[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?

 

[quasar987]

Try integration by parts.

 

[HallsofIvy]

Let u= x, dv= e^-xdx.

 

[Count Iblis]

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