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Math Help - Non-real critical values possible?

  1. #1
    Junior Member beebe's Avatar
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    Non-real critical values possible?

    The question in question:

    Find the critical numbers of the function f(x)=2x^3+x^2+2x.

    I know that f'(x)=6x^2+2x+2=2(3x^2+x+1).

    Solving using the quadratic formula gives me x=\frac{-1\pm\sqrt{11}i}{6}

    I'm only taking Calc 1, so I figured that I should just say that there aren't any critical values, but do non-real values count?
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  2. #2
    MHF Contributor
    skeeter's Avatar
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    Re: Non-real critical values possible?

    Quote Originally Posted by beebe View Post
    The question in question:

    Find the critical numbers of the function f(x)=2x^3+x^2+2x.

    I know that f'(x)=6x^2+2x+2=2(3x^2+x+1).

    Solving using the quadratic formula gives me x=\frac{-1\pm\sqrt{11}i}{6}

    I'm only taking Calc 1, so I figured that I should just say that there aren't any critical values, but do non-real values count?
    not if you're studying calculus of a real variable (which you most probably are)
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