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Math Help - factoring higher quadratics

  1. #1
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    factoring higher quadratics

    Solve by factoring
    x^4-12x^2-64=0
    How? -.-
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  2. #2
    Senior Member Stroodle's Avatar
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    Quote Originally Posted by m0nkeysensei View Post
    Solve by factoring
    x^4-12x^2-64=0
    How? -.-
    Let x^2=y

    Then you have:

    y^2-12y-64=0

    (y+4)(y-16)=0

    So,

    (x^2+4)(x^2-16)=0

    (x^2+4)(x+4)(x-4)=0

    \therefore x=\pm 4 and x=\pm 2i
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