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Math Help - Please check my working out

  1. #1
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    Please check my working out

    Hi all,

    Given this question and was hoping you can check my working out.

    Find x in terms of c, given that (2 / 3x-2c) + (3 / 2x-3c) = (7 / 2c)

    4c(2x-3c) + 6c(3x-2c) = 7(3x-2c)(2x-3c)
    8xc 12c + 18xc 12c = 7(6x - 9xc 4xc + 6c)
    8xc 12c + 18xc 12c = 42x - 91xc + 42c
    42x - 117xc + 76c = 0
    x = 117c √(117c) - 4 (42)(76c)
    2(42)
    x = 117c √(117c) - 12768
    84
    x = 117c √921c
    84

    Cheers
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  2. #2
    MHF Contributor Amer's Avatar
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    Quote Originally Posted by Joel View Post
    Hi all,

    Given this question and was hoping you can check my working out.

    Find x in terms of c, given that (2 / 3x-2c) + (3 / 2x-3c) = (7 / 2c)

    4c(2x-3c) + 6c(3x-2c)          =              7(3x-2c)(2x-3c)

    8xc - 12c^2 + 18xc -12c^2    =              7(6x^2 - 9xc - 4xc + 6c^2)

    8xc-  12c^2 + 18xc - 12c^2    =              42x - 91xc + 42c^2

    42x^2 - 117xc +{\color{red} 76}c^2             =              0


    x = 117c √(117c) - 4 (42)(76c)
    2(42)
    x = 117c √(117c) - 12768
    84
    x = 117c √921c
    84


    Cheers

    4c(2x-3c) + 6c(3x-2c) = 7(3x-2c)(2x-3c)

    8xc - 12c^2 + 18xc -12c^2 = 7(6x^2 - 9xc - 4xc + 6c^2)

    8xc- 12c^2 + 18xc - 12c^2 = 42x^2 - 91xc + 42c^2

    42x^2 - 117xc + {\color{red}76}c^2             =              0

    {\color{blue}42x^2 - 117xc +66c^2            =              0}

    x=\frac{117\pm \sqrt{13689c^2-11088c^2}}{84}

    x=\frac{117\pm \sqrt{2601c^2}}{84}

    x=\frac{117\pm 51c}{84}
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  3. #3
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    what a difference 10 can make. lol

    Thanks heaps
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