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Math Help - quadratic equation problem

  1. #1
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    quadratic equation problem

    Could someone please show me where I went wrong on this:

    2x^2+2x-12=0
    2x^2 +6x-4x-12=0
    x(2x+6)(-4x-12)=0
    2x+6=0,2x=-6,
    2x/2=-6/2,x=-3

    -4x=12,-4x/4=12/4
    x=3
    Last edited by wolfhound; October 6th 2009 at 05:17 AM. Reason: messy
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  2. #2
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    Quote Originally Posted by wolfhound View Post
    Could someone please show me where I went wrong on this:

    2x^2+2x-12=0
    2x^2 +6x-4x-12=0
    x(2x+6)(-4x-12)=0 <<<<<<<<< here
    2x+6=0,2x=-6,
    2x/2=-6/2,x=-3

    -4x=12,-4x/4=12/4
    x=3
    I take this line:

    2x^2 +6x-4x-12=0~\implies~2x(x+3)-4(x+3)=0~\implies~(x+3)(2x-4)=0

    I'll leave the rest for you
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  3. #3
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    Smile

    Quote Originally Posted by earboth View Post
    I take this line:

    2x^2 +6x-4x-12=0~\implies~2x(x+3)-4(x+3)=0~\implies~(x+3)(2x-4)=0

    I'll leave the rest for you
    x=-3 and x=2
    Thanks
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