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Math Help - [SOLVED] Finding the unknown c?

  1. #1
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    [SOLVED] Finding the unknown c?

    If the sum of the roots of the equation cx^2 - (1 + c)x + 3c + 2 = 0 is equal to twice the product of the roots, find the value of c and the two roots.

    \alpha + \beta = \frac{1+c}{c}

    \alpha\beta = \frac{3c + 2}{c}

    Then, I solved the rest and finally I got,

    c(5c + 3) = 0

    So, c = 0 or c = \frac{-3}{5}

    But in my answer book, the answer for c is \frac{-3}{5} only. Why is it so?
    Last edited by mark1950; June 30th 2009 at 01:51 AM.
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  2. #2
    MHF Contributor alexmahone's Avatar
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    When c=0, the equation is no longer a quadratic. Hence that root is rejected.
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