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Evaluating derivatives

  1. Mar 1, 2014 #1
    1. The problem statement, all variables and given/known data

    So I'm trying to find dy/dt. I used the chain rule to find dx/dt. I just don't understand how to put that answer back into an equation to find dy/dt

    2. Relevant equations

    4x^3-6xy^2+3y^2=228

    3. The attempt at a solution
    I found dx/dt=3 x=-3 and y=4
    So how/what equation do I use to find dy/dt
     
  2. jcsd
  3. Mar 1, 2014 #2

    Dick

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    Differentiate 4x^3-6xy^2+3y^2=228 with respect to t, put your values for x, y and dx/dt into that and solve for dy/dt.
     
  4. Mar 1, 2014 #3
    The implicit differentiation?
     
  5. Mar 1, 2014 #4

    Dick

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    Of course.
     
  6. Mar 1, 2014 #5
    I got dy/dt=(2x^2-y^2)/(y(2x-1))
     
  7. Mar 1, 2014 #6

    Dick

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    An expression for dy/dt ought to have some dx/dt's in it. I think what you've got there is dy/dx. Can you think how to use that to get dy/dt?
     
  8. Mar 1, 2014 #7
    Yep! I figured it out. Thank you!
     
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