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Homework Help: Easy derivative

  1. Nov 19, 2008 #1
    1. The problem statement, all variables and given/known data
    y=x2/3(x2-4)



    2. Relevant equations



    3. The attempt at a solution
    1.y'=2/3x-1/3(x2-4)+x2/3*2x

    2.y'=2x2-8+2x5/2/3(x1/3)

    the book agrees with my unsimplified (#1)derivative but it goes further to simplify the equation as
    y'= 8x2-8/3(x1/3)

    I can't see how they got 2(x2-4)+x2/3*2x to be 8x2-8
    in the numerator.
    Would someone explain this to me?
     
  2. jcsd
  3. Nov 19, 2008 #2

    Mark44

    Staff: Mentor

    It's difficult to tell in your second expression what's in the numerator and what's in the denominator.

    Is 8x^2 - 8 in the numerator?
    Are both 3 and x^(1/3) in the denominator?

    I can't explain it to you if I don't know what you wrote.
     
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