## anonymous 4 years ago Need help with this integration by parts question. The answer I gave, which is in the gray box, is wrong.

1. anonymous

2. LollyLau

so you're integrating x^2e^-x from 0 to x.

3. LollyLau

nvm

4. anonymous

@LollyLau, that is what I integrated for

5. anonymous

You almost had it. You got the correct antiderivative, $-x^2e^{-x}-2xe^{-x}-2e^{-x}$ But you didn't answer the question, it wants the integral of the original function from x=0 to a. So you must do $\left(-x^2e^{-x}-2xe^{-x}-2e^{-x}\right|_0^a=-a^2e^{-a}-2ae^{-a}-2e^{-a}+2$

6. Zarkon

shouldn't your answer be in terms of a

7. anonymous

Thanks Imperialist and Zarkon, you're both gentlemen and scholars. I attached the screenshot of the right answer.