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Math Help - relative minimum

  1. #1
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    relative minimum

    Let f be the function given by f(x)= x^4/16-x^3+3x^2/8-2x. The function f has a relative minimum at x=

    Thanks.

    I took the derivative to get f'(x)=x^3-12x^2+3x-8 and set that equal to zero...then synthetic division??
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  2. #2
    Moo
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    Hello,

    Watch out, you have to solve f'(x)=0, so you can simplify by 4, but it's completely incorrect to say that f'(x)=x^3-12x^2+3x-8

    f'(x)=1/4*(x^3-12x^2+3x-8)
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  3. #3
    MHF Contributor Mathstud28's Avatar
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    If this is supposed to be

    \frac{x^4}{16}-x^3+\frac{3x^2}{8}-2x...then the derivative is f'(x)=\frac{x^3}{4}-3x^2+\frac{3x}{8}-2 then use either, graphing calculator, newton's approximation, or use intermediate value theorem noting f'(11)=\frac{-225}{8} and f'(12)=\frac{5}{2}
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