Trying to do the indefinate integral of x^3 * (9-x^2)^1/2 by using the substitution of x = 3 sin u I get 81* integral[ (sin^3 u)(cos u)] but again I appear to be wrong.

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- June 3rd 2008, 10:07 PMCrakaIntegration by trig substitution
Trying to do the indefinate integral of x^3 * (9-x^2)^1/2 by using the substitution of x = 3 sin u I get 81* integral[ (sin^3 u)(cos u)] but again I appear to be wrong.

- June 3rd 2008, 10:24 PMo_O

I think you forgot to make the sub for dx. This last integral should be straightforward. Make the substitution s = sin u and you should be on your way ;) - June 3rd 2008, 11:27 PMCraka
Thanks for that you are right I had forgot to sub in the dx value. How do you guys use the correct mathmatic symbols in the post?

- June 4th 2008, 02:19 PMebaines