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Math Help - Equation help!!!!!

  1. #1
    midnightskate3
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    Equation help!!!!!

    how do u find the roots of the equation 2xsquared+7x-1=0
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by midnightskate3 View Post
    how do u find the roots of the equation 2xsquared+7x-1=0
    use the quadratic formula

    for a quadratic of the form y = ax^2 + bx + c, the roots are given by:

    x = \frac {-b \pm \sqrt{b^2 - 4ac}}{2a}
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  3. #3
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by midnightskate3 View Post
    how do u find the roots of the equation 2xsquared+7x-1=0
    Or you can complete the square:
    2x^2 + 7x - 1 = 0

    2x^2 + 7x = 1

    2 \left ( x^2 + \frac{7}{2} \right ) = 1

    2 \left ( x^2 + \frac{7}{2}  + \frac{49}{4} \right ) = 1 + 2 \cdot \frac{49}{4}

    2 \left ( x + \frac{7}{2} \right ) ^2  = \frac{51}{2}

    \left ( x + \frac{7}{2} \right ) ^2  = \frac{51}{4}

    x + \frac{7}{2} =  \pm \sqrt{\frac{51}{4}}

    x = -\frac{7}{2} + \pm \frac{\sqrt{51}}{2}

    (If you want more details, just ask. )

    -Dan
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