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Math Help - How do I find these derivatives?

  1. #1
    Junior Member
    Joined
    Sep 2010
    Posts
    48

    How do I find these derivatives?

    Suppose f and g are differentiable functions with the values shown in the table below. For each of the following functions h, find h '(4).


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


    (a) h(x) = f(x) + g(x)

    h'(4)= __________

    (b) h(x) = f(x) g(x)

    h'(4)= __________

    (c) h(x) = f(x) / g(x)

    h'(4)= __________

    Could someone explain how to go about doing this please?

    Thank you!
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  2. #2
    Junior Member
    Joined
    May 2009
    Posts
    42
    Hey,

    You are just solving the derivatives like normal but it is written in a strange way that may seem confusing at the first time.

    For a) for instance, imagine f(x) to be x^2 and g(x) to be x

    therefore h(x) = x^2 + x right? when you take the derivative of h(x) you take the derivative of each term.... so in my made up example h'(x) = 2x + 1 right?

    The examples given are exactly the same. h(x) = f(x) + g(x) so..........
    h'(x) = f'(x) + g'(x)

    After that you can finally use the information given;
    h'(4) = f'(4) + g'(4), and from the table you know those two values, so
    h'(4) = 3 + (-2) = 1

    Simply follow these steps and basic derivative steps to solve b) and c)
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  3. #3
    Junior Member
    Joined
    Sep 2010
    Posts
    48
    OOH silly me hahah. The wording of the problem confused me. Thank you very much =)
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