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Homework Help: Taking a derivative

  1. Jul 9, 2010 #1
    1. The problem statement, all variables and given/known data

    6x/(x2+3)2


    3. The attempt at a solution
    If I solve this function as a multiplication, i.e.

    6x (x2+3)-2

    my answer is

    f ' (x)=[ (x-3)(x-1) ]/(x2+3)3

    If I solve it as a fraction
    f ' (x)=(v'g-g'v)/g2

    I get

    f ' (x)=(x2-1)/(x2+3)3


    This is all so confusing. Please help me out. Thank you.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jul 9, 2010 #2

    vela

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    Neither is correct. Show us your steps so we can see where your mistakes lie.
     
  4. Jul 10, 2010 #3
    6x (x2+3)-2


    Did you use the product rule followed by the chain rule?

    You can consider this function as:

    h(x)=f(x)g(p(x))

    where:

    f(x)=6x, g(z) = z-2 ,and p(x)=x2+3

    Now how would you take the derivative of h(x)?

    Hint: h'(x)=f'(x)g(p(x))+f(x)g'(p(x))p'(x)
     
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