Math Help - graphing problems

1. graphing problems

Let R be the region in the first quadrant enclosed by the graphs of y=xe^-x, x=0, x=k for k>0. The area of R, in terms of k, is

A) -k-1/e^k
b)k^2/2e^k
c)k-1-e^k/e^k
d) e^k-k-1/e^k
e) ke^k-e^k+1

2. Originally Posted by sandiego234
Let R be the region in the first quadrant enclosed by the graphs of y=xe^-x, x=0, x=k for k>0. The area of R, in terms of k, is

A) -k-1/e^k
b)k^2/2e^k
c)k-1-e^k/e^k
d) e^k-k-1/e^k
e) ke^k-e^k+1
$\int_0^{k}xe^{-x}dx=[-xe^{-x}-e^{-x}]\bigg|_0^{k}=(-k-1)e^{-k}+1$

3. Upon further review, I don't think this matches up with any of the answers.

I did integration by parts ....

Anyone? THanks you.

4. Originally Posted by sandiego234
Upon further review, I don't think this matches up with any of the answers.

I did integration by parts ....

Anyone? THanks you.
I am pretty sure this is the right answre Sandiego234...I did do integration by parts