- hello again :)

im working my way thourgh the awesome calculus tutorial but now im stuck at one point:

$\displaystyle \int x^2 e^x

$

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- Jun 7th 2009, 10:20 AMcoobeQuestion to Calculus Tutorial
- hello again :)

im working my way thourgh the awesome calculus tutorial but now im stuck at one point:

$\displaystyle \int x^2 e^x

$ - Jun 7th 2009, 10:29 AMTheEmptySet
- Jun 7th 2009, 10:45 AMcoobeQuestion to Calculus Tutorial
$\displaystyle \int x^2 e^x$

$\displaystyle \\u = x^2\\$

$\displaystyle \\v'=e^x\\$

$\displaystyle \\u'=2x\\$

$\displaystyle \\v =e^x\\$

$\displaystyle \\x^2e^x-\int 2xe^xdx = x^2 e^x -2\int x e^x$

everything clear so far. but now it seems the author is missing an $\displaystyle e^x$

the given solution: $\displaystyle x^2-2xe^x+2e^x+C$

is it just a typo or am i missing something ? - Jun 7th 2009, 10:58 AMChop Suey
You're right. It should've been:

$\displaystyle x^2e^x - 2xe^x + 2e^x + C$

You can always to differentiate your answer and see if you get your original integrand. That way you can make sure if you got it right or not. - Jun 7th 2009, 02:05 PMHallsofIvy