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Thread: find the solution set of the equation

  1. December 11th 2007, 04:39 AM #1
    lovely08
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    find the solution set of the equation

    2/5x - x/4 = 4
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  2. December 11th 2007, 05:00 AM #2
    colby2152
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    Quote Originally Posted by lovely08 View Post
    2/5x - x/4 = 4
    \frac{2}{5x} - \frac{x}{4} = 4

    Find a common denominator. Easy way to do that is multiply all denominators with each other: 5x*4 = 20x. Now, multiply the entire equality by 20x (same as multiplying each term by 20x).

    \frac{40x}{5x}- \frac{20x^2}{4} = 80x

    Simplify it...

    8-5x^2=80x
    5x^2+80x-8

    Quadratic formula will solve it...

    x = \frac{-80 \pm \sqrt{80^2 - 4(-8)(5)}}{10}
    x = \frac{-80 \pm -80.994}{10}
    x = -8 \pm - 8.0994
    x = 0.0994, -16.0994
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