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Homework Help: Implicit differentiation dy/dx

  1. Apr 18, 2010 #1
    1. The problem statement, all variables and given/known data
    Determine dy/dx
    xy^-2 = 1

    2. Relevant equations

    3. The attempt at a solution
    Here's what I tried:
    y^-2 - 2xy^-3(dy/dx) = 1
    dy/dx = (y - y^3)/2x

    The answer in the book is y/2x. How do you do it?
  2. jcsd
  3. Apr 18, 2010 #2


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    Homework Helper

    You differentiated the left side but not the right side

    d/dx(1) = ?
  4. Apr 18, 2010 #3
    Thanks. Duh.
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