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Math Help - Quadratic Formula.

  1. #1
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    Quadratic Formula.

    Can anyone help me understand how we get from

    \frac{1}{8}(56 \pm \sqrt{64 +16y})

    to

    7 \pm \sqrt{1 + \frac{1}{4}y}

    thanks
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  2. #2
    Junior Member mathfun's Avatar
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    $$\tfrac{1}{8}\left( {56 \pm \sqrt {64 + 16y} } \right) = \tfrac{{56}}{8} \pm \tfrac{{\sqrt {64 + 16y} }}{8} = 7 \pm \tfrac{{\sqrt {64} \sqrt {1 + \tfrac{1}{4}y} }}{8} = 7 \pm \sqrt {1 + \tfrac{1}{4}y} $$
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  3. #3
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    so like

    \sqrt{64+16y} = \sqrt{64(1 + \frac{1}{4}y)} = \sqrt{64} \sqrt{1 + \frac{1}{4}y}

    ?
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  4. #4
    Junior Member mathfun's Avatar
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    yeap.
    Just keep in mind that $$\sqrt {a \cdot b}  = \sqrt a  \cdot \sqrt b $$
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