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

Question

anonymous · Answer

attachment

lollylau · Answer

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

lollylau · Answer

nvm

anonymous · Answer

@LollyLau, that is what I integrated for

anonymous · Answer

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 $$\left(-x^2e^{-x}-2xe^{-x}-2e^{-x}\right|_0^a=-a^2e^{-a}-2ae^{-a}-2e^{-a}+2$$

zarkon · Answer

shouldn't your answer be in terms of a

anonymous · Answer

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