## anonymous 5 years ago Does anybody know how to do complex integral substitution?

1. anonymous

i do not know

2. anonymous

Some of the guys here are pretty good. Post question.

3. anonymous

Okay, thanks

4. anonymous

You welcome

5. anonymous

i give everyone medals

6. anonymous

$\int\limits_{}^{}x ^{2}(x ^{3}+5)^{9} dx$

7. anonymous

let u = x^3+5, so du = 3x^2dx the integral becomes$(1/3)\int\limits_{}^{}u^9du$ then you integrate, so the final answer then is (1/30)(x^3+5)^10 + C

8. anonymous

Mika, this is a straight forward u-sub, the way you complex integral, I thought it was out of my league and didn't even attempt it.

9. anonymous

how could it possibly be out of your league Chagauna? I'm glad you agree on the answer though. I might be all bugged out telling him to let u be something like that. I'll bet Mika's dealling with integrals like that and those kinds of methods as we speak. I might as well just let him get the answer though, so he feels like he can take it all from there. I bet he does great. Thanks for the reinforcement.

10. anonymous

OK, I won't get intimidated next time someone say I have a 'complex' problem.

11. anonymous

But this is always a clue, Mika, the derivative of x^3+5 is 2x dx which is part of the question.