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Math Help - Complex numbers (roots of equations) help

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    Complex numbers (roots of equations) help

    Using that 3 is the real root of the cubic equation x^3-27=0, show that the complex roots of the cubic satisfy the quadratic equation x^2+3x+9=0.

    hence or otherwise find the three cube roots of 27 giving your answers in the form a+ib

    thankyou!
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    Re: Complex numbers (roots of equations) help

    Quote Originally Posted by ineedmathshelp View Post
    Using that 3 is the real root of the cubic equation x^3-27=0, show that the complex roots of the cubic satisfy the quadratic equation x^2+3x+9=0. hence or otherwise find the three cube roots of 27 giving your answers in the form a+ib
    Given that 3 is root of x^3-27=0 means that (x-3)
    is a factor. So (x-3)(?)=x^3-27.
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