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Homework Help: I feel stupid asking but

  1. Apr 21, 2005 #1
    Okay, I feel really dumb, because this seems like something I should know, but I don't. So, here's my question.

    Suppose I have d2y/dx2, x = x(z), and z = z(x)
    How do I find d2y/dz2?
    Here's what I did:

    dy/dz = dy/dx * dx/dz
    d2y/dz2 = d/dz ( dy/ dz ) = d/dz (dy/dx * dx/dz)
    = d2y/dx2 * (dx/dz)^2 + dy/dx * d2x/dz2

    Is that OK? Is there an easier way to do this?
  2. jcsd
  3. Apr 21, 2005 #2


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    Homework Helper

    Nope.2 times chain rule required by the implicite dependence upon a variable...

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