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Math Help - f'(x)?

  1. #1
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    f'(x)?

    find f'(x) if it is known that
    d/dx [f(2x)]=x2

    what does this mean?
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  2. #2
    MHF Contributor MarkFL's Avatar
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    Re: f'(x)?

    We are told:

    \frac{d}{dx}(f(2x))=x^2

    Using the chain rule, we find:

    2f'(2x)=x^2

    f'(2x)=\frac{x^2}{2}=\frac{4x^2}{8}=\frac{(2x)^2}{  8} and so we must have:

    f'(x)=\frac{x^2}{8}
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