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Homework Help: If P(x) = g^2(x), then P'(3) = ?

  1. Feb 1, 2010 #1
    1. The problem statement, all variables and given/known data
    If P(x) = g^2(x), then P'(3) =


    2. Relevant equations



    3. The attempt at a solution
    I am not quite sure what g^2(x) means...
    But my assumption is do the derivative of g^2(x), so it becomes 2g(x), then put the 3 in for x?
    so the final answer will be 2g(3) ?
    It looks weird to me, so I am not sure if I am doing it correctly or not.

    Please advise, thank you.
     
  2. jcsd
  3. Feb 1, 2010 #2
    Almost! you need to apply chain rule!
     
  4. Feb 1, 2010 #3

    Mark44

    Staff: Mentor

    Also, your inclination that g2(x) = g(x)*g(x) is correct.
     
  5. Feb 1, 2010 #4
    To sutupidmath,
    Thank you!
    So it should be 2g(x)g'(x), thus the final answer for that question would be P'(3) = 2g(3)g'(3).

    To Mark44
    I got confused a little there because I thought the final answer was different from 2g(x) (which was the wrong answer anyways). Now I redid the problem using product rule instead for g(x)g(x), and my derivative turned out to be g'(x)g(x) + g(x)g'(x), which is the same as 2g(x)g'(x) anyways :D

    Thank you so much to both of you.
     
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