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
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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 $\displaystyle \int_0^{k}xe^{-x}dx=[-xe^{-x}-e^{-x}]\bigg|_0^{k}=(-k-1)e^{-k}+1$
Last edited by Mathstud28; Apr 29th 2008 at 06:33 PM.
Upon further review, I don't think this matches up with any of the answers. I did integration by parts .... Anyone? THanks you.
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
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