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Offline houmeira

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MATHS/ Integration P3
« on: October 19, 2009, 06:18:26 pm »
hi!
Can anyone please help to solve this question?

integral of x2ex3 dx.

would you also show me the method. i'm trying integration by parts but im getting stuck!
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Offline astarmathsandphysics

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Re: MATHS/ Integration P3
« Reply #1 on: October 19, 2009, 07:19:26 pm »
Not integration by parts. Is integration by substitution. Sub u=x3. Will answer when i get home.
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Offline astarmathsandphysics

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Re: MATHS/ Integration P3
« Reply #2 on: October 19, 2009, 09:17:53 pm »
\int x^2 e^{x^3} dx
sub u=x^3 so du=3x^2 dx so dx=\frac {du}{3x^2}
Integral becomes \int x^2 e^{u} \frac {du}{3x^2} =\frac {1}{3} \int e^u du =\frac {1}{3} e^u =\frac {1}{3} e^{x^3}
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Offline houmeira

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Re: MATHS/ Integration P3
« Reply #3 on: October 20, 2009, 03:42:12 am »
Thank you very much!!!i've got exams so thanks:))you're great!
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