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Homework Help: Product rule error help

  1. Sep 8, 2008 #1
    y = ( 5 x-2 ) 3 / ( 2 x+5 ) 4

    I do it this way:

    f(x) = (5x-2)3
    g(x) = (2x+5)-4
    f'(x) = 3(5x-2)2
    g'(x) = -4(2x+5)-5

    By using the product rule:

    [3(5x-2)2](2x+5)-4 + (5x-2)3[-4(2x+5)-5]
    3(5x-2)2(2x+5)-4 -4(2x+5)-5(5x-2)3

    What's wrong with this answer?
     
  2. jcsd
  3. Sep 8, 2008 #2

    berkeman

    User Avatar

    Staff: Mentor

    Re: Differentiation

    Thread moved to Homework Help

    I do not believe you have differentiated correctly in these steps.
     
  4. Sep 8, 2008 #3
    Re: Differentiation

    Is it this way??

    f'(x) = 15(5x-2)2
    g'(x) = -8(2x+5)-5
     
    Last edited: Sep 8, 2008
  5. Sep 8, 2008 #4
    Re: Differentiation

    Yes, got it. Thanks for pointing out the error.
     
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