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- May 10th 2007, 04:49 PMqbkr21Integrals #2
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- May 10th 2007, 05:13 PMqbkr21Re:
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- May 10th 2007, 05:24 PMalinailiescuintegral 2
See a different substitution which works better.

- May 10th 2007, 05:32 PMqbkr21Re:
What made you choose just x^2? How do you determine that?:eek:

- May 10th 2007, 05:37 PMalinailiescu
Just intuition, and a lot of experience:)

Regarding your question about dividing the integral, you can do that as long you know that both function you use are integrable. - May 10th 2007, 05:37 PMqbkr21Re:
Is this something that comes across often? And is this one of the first things you look for when you are solving these kinds of problems?

- May 10th 2007, 05:49 PMqbkr21Re:
Also two other questions...

1) Do all constants hold over? No matter if they are from the original problem or from the differentiation of U?

2) If there is a plus or minus a number in the original problem, do I put that out in front of the integral and let it hold over, or do I integrate at the same time I integrate Ul? - May 10th 2007, 06:15 PMalinailiescu
My rule to choose substitution is whatever you don't like replace with a new letter. You tried that, but it didn't give you a simpler integral. I know that I have to change x^4, since a linear expresion did not work, a quadratic on the bottom I can deal with.

If you have square roots, or radical, almost all the times works by using a new variable for the whole radical. - May 10th 2007, 06:20 PMalinailiescu