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Math Help - Derivative problem, where f is a differentiable function.

  1. #1
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    Derivative problem, where f is a differentiable function.

    If f is a differentiable function, find an expression for the derivative of each of the following functions:

    a) g(x)= f(x^2)
    This one I am having trouble with. I applied chain rule to solve, which gave me g'(x)= f'(x^2)*(2x), but the answer in the book says its supposed to be f(x^2)*(2x). What am I doing wrong?

    b) h(x)= 2xf(x)
    I answered this using product rule,
    h'(x)= (2)f(x)+(2x)f'(x)
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  2. #2
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    Quote Originally Posted by ibetan View Post
    If f is a differentiable function, find an expression for the derivative of each of the following functions:

    a) g(x)= f(x^2)
    This one I am having trouble with. I applied chain rule to solve, which gave me g'(x)= f'(x^2)*(2x), but the answer in the book says its supposed to be f(x^2)*(2x). What am I doing wrong?

    b) h(x)= 2xf(x)
    I answered this using product rule,
    h'(x)= (2)f(x)+(2x)f'(x)
    There is nothing wrong other than a typo in the book.

    CB
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