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Homework Help: Integration of Function of Two Variables

  1. Sep 29, 2010 #1
    1. The problem statement, all variables and given/known data

    For one of my physics classes I need to integrate a function of two variables, but I haven't learned how to do it yet in my calculus classes. If anyone could explain to me how to do it, it would be much appreciated. It's probably pretty simple I just haven't learned it yet.

    the integral is [tex]\int[/tex] (z 2 + x2)-3/2 dx

    and i know that the answer is x/ sqrt (z2 + x2) z2

  2. jcsd
  3. Sep 29, 2010 #2

    Char. Limit

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    Gold Member

    z^2 is a constant with respect to x. That might help.
  4. Sep 29, 2010 #3
    yea I've been trying to think of it that way but everything i do doesn't end up working and I can't think of anything else to do
  5. Sep 29, 2010 #4
    You can make a trig substitution.
  6. Sep 29, 2010 #5
    I think I understand where the sqrt(z2 + x2) in the denominator of the answer comes from, if you pretend z2 + x2 is one term and take its anti-derivative you get 1/sqrt(z2 + x2), but i dont know where the x in the numerator or the z2 in the denominator come from
  7. Sep 29, 2010 #6
    What happens if you make x= ztan[tex] \theta[/tex].
  8. Sep 29, 2010 #7
    oh wow thank you so much, I completely forgot about trig substitution. Thanks a lot I just got it
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