[tex]\int \frac{x}{\left(x^2+z^2\right)^{3/2}} \, dx[/tex]

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Homework Statement


\int \frac{1}{\left(x^2+z^2\right)^{3/2}} \, dx

I have been trying various u-substitutions for about 2 hours now, but I cannot seem to find a way to solve this by hand! I used mathematica to solve the problem. I feel like it will be fairly straightforward once I figure out what u should be, if u-sub is the way to go.

This is for my electrodynamics course, and getting hung up on integrals is not helpful.

I've tried:
u=x^2
u=1/(x2+z2)1/2
u=1/(x2+z2)
u=1/(x2+z2)3/2
u=x/(x2+z2)1/2
u=x/(x2+z2)
u=(x2+z2)1/2
u=(x2+z2)
u=(x2+z2)3/2
 
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Have you tried a trig substitution...something like x=z\tan\theta looks appropriate:wink:
 
wow...never even crossed my mind to use trig substitution. In fact, I completely forgot that as a method. And its so useful! Thank you! I guess I ought to review calc 2 stuff from HS...

Thanks again!
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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