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Math Help - radical equation problem help

  1. #1
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    radical equation problem help

    \sqrt{x+7}-2\sqrt{x}=-2

    \left(\sqrt{x+7}\right)^2=\left(-2+2\sqrt{x}\right)^2

    x+7=4-8\sqrt{x}+4x

    \left(-3x-3\right)^2=\left(-8\sqrt{x}\right)^2

    9x^2+18x+9=64x

    9x^2-46x+9=0

    iam lost after that, reviewed it and cant figure out what went wrong, the answer is 9
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  2. #2
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    Re: radical equation problem help

    Quote Originally Posted by mathmathmathmathmathmathm View Post
    \sqrt{x+7}-2\sqrt{x}=-2

    \left(\sqrt{x+7}\right)^2=\left(-2+2\sqrt{x}\right)^2

    x+7=4-8\sqrt{x}+4x

    \left(-3x-3\right)^2=\left(-8\sqrt{x}\right)^2 this line ... should be (-3x+3)^2 on the left side
    ...
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