# integration help

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• Oct 17th 2009, 02:28 PM
messianic
integration help
I need help integrating teh following functioN:

(x^3)(e^(x^2)
• Oct 17th 2009, 02:33 PM
Chris L T521
Quote:

Originally Posted by messianic
I need help integrating teh following functioN:

(x^3)(e^(x^2)

Apply the substitution $u=x^2$ to get $\tfrac{1}{2}\int ue^u\,du$.

Then apply integration by parts.

Can you take it from here?
• Oct 17th 2009, 02:51 PM
messianic
well it is x^3 so the u in the integral should be u^3/2 right? This complicates things. Can you explain further
• Oct 17th 2009, 03:01 PM
mr fantastic
Quote:

Originally Posted by messianic
well it is x^3 so the u in the integral should be u^3/2 right? This complicates things. Can you explain further

Wrong. Have you been taught how to do a 'u-substitution' when integrating?
• Oct 17th 2009, 03:21 PM
messianic
yes but a while ago.

can you please explain it?
• Oct 17th 2009, 03:34 PM
mr fantastic
Quote:

Originally Posted by messianic
yes but a while ago.

can you please explain it?

First go back to your class notes or textbook and review the technique. Note that Google will also give many websites that review the technique.