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Math Help - Simultaneous equations

  1. #1
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    Simultaneous equations

    Find the value of m for which the simultaneous equations
    (m + 3)x + my = 12
    (m + 1)x + (m - 3)y = 7
    have no solution.

    I am insure what to do here! Do I need to set them up in a matrix or...
    Any help would be appreciated! Thanks
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  2. #2
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    Quote Originally Posted by scubasteve94 View Post
    Find the value of m for which the simultaneous equations
    (m + 3)x + my = 12
    (m + 1)x + (m - 3)y = 7
    have no solution.

    I am insure what to do here! Do I need to set them up in a matrix or...
    Any help would be appreciated! Thanks
    There will not be a solution if the two linear equations are parallel.

    Rewrite them in y = ax + b form.


    y = -\frac{m + 3}{m}x + \frac{12}{m}

    y = -\frac{m + 1}{m - 3}x + \frac{7}{m - 3}.


    Since they are parallel, the gradients are the same.

    So -\frac{m + 3}{m} = -\frac{m + 1}{m - 3}

    (m + 3)(m - 3) = m(m + 1)

    m^2 - 9 = m^2 + m

    m = -9.
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