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Homework Help: Implicit Differentiation concept help?

  1. Mar 18, 2012 #1
    1. The problem statement, all variables and given/known data
    Its not homework, i have the answer im just having a hard time wrapping my head around the concept of differentiating implicitly defined functions.

    the question was: x^3+y^3=3xy, find the equation of the tangent line at the point (3/2,3/2).


    2. Relevant equations
    x^3+y^3=3xy


    3. The attempt at a solution

    so what my prof did was:
    1)x^3+y^3=3xy
    2)3x^2+3y^2(dy/dx)=3y+3x(dy/dx)

    i get the part on the left, but i dont understand how he got the part on the right... :/

    if anyone could just elaborate on the steps in between those two it would be much appreciated for my understanding. thank you.
     
  2. jcsd
  3. Mar 18, 2012 #2
    ah nevermind I got it, silly really. how can i delete this thread?
     
  4. Mar 18, 2012 #3

    Dick

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    Your prof used the product rule on the right side.
     
  5. Mar 18, 2012 #4
    yeah. i feel extremely silly for asking. ive been staring at the screen for too long at these examples. any way to delete this cause its 'solved'? or do i just sort of leave it.
     
  6. Mar 18, 2012 #5

    Dick

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    Oh, just leave it. It's no big deal. Everybody has their silly moments. Sometimes just posting a question helps you think.
     
  7. Mar 18, 2012 #6
    Yeah, typing it out defs helped. Alright, just gonna leave it then.
     
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