How would I work the integral:

x^3 * sqrt(x^2 -9) dx

without using trig substitution? My professor said that it is a way, but I don't see it!

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- Jul 11th 2009, 06:26 AMlataveeIntegration without Trig Sub
How would I work the integral:

x^3 * sqrt(x^2 -9) dx

without using trig substitution? My professor said that it is a way, but I don't see it! - Jul 11th 2009, 06:45 AMCaptainBlack
- Jul 11th 2009, 07:22 AMlataveeTHanks!
AH! Never thought of that! Thank you!

- Jul 11th 2009, 07:37 AMhalbard
How about the substitution or equivalently ? Then and you end up with a polynomial in to integrate.

- Jul 11th 2009, 10:08 AMHallsofIvy
I would do by writing it as and using the substitution . Then du= 2xdx so and . That gives

- Jul 11th 2009, 10:31 AMlatavee
I'm going to try some of these ideas out! and I will see if I can come up with the answer that I had using trig substitution/or nearly the same! Thanks guys!