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Homework Help: Expressed all partial derivatives

  1. Apr 24, 2005 #1
    I'm given F(x*y;z/x), where z=z(x,y).
    I have to proof that (∂z/∂x)*x+(∂z/∂y)*y=3*z
    I have expressed all partial derivatives, but I got only (∂z/∂x)*x-(∂z/∂y)*y=z
    I think that it's impossible at all to solve this problem, because z is arbitrary function as i understand.
    Help me please. Where I'm wrong?
  2. jcsd
  3. Apr 24, 2005 #2
    I made it. And received (∂z/∂x)*x-(∂z/∂y)*y=z
    Did anyone get (∂z/∂x)*x+(∂z/∂y)*y=3*z ??
    I've denoted already many hours for this problem and many times got "incorrect" answer. Now I think that my solution is correct and something is wrong with a "handwritten answers" on the sheet with problems
  4. Apr 24, 2005 #3


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    Science Advisor
    Homework Helper

    Have you stated the problem correctly?

    Consider the variables u = x*y and v = z/x and take the partial derivatives of F using the chain rule
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