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Math Help - Need help Confused

  1. #1
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    Need help Confused

    I have been trying to do this problem and I do not know where to start.
    What is throwing me off is y/4. I have looked in my textbook and I can not find any example of this problem. I hope someone can help me.

    Use elimination to solve: 6x - y/4 = -9 and 3x + 2y = -30


    Thank you for the help in advance.
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  2. #2
    MHF Contributor
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    " Use elimination to solve: 6x - y/4 = -9 and 3x + 2y = -30 "

    Elimination here means eliminating/removing one of the variables. So if your problem is the y/4, then eliminate the y's. The other y-term is 2y, so you either
    >>>make this 2y into y/4 by dividing 2y by 8, or,
    >>>make the y/4 into 2y by multiplying the y/4 by 8. It is better this way so that you can avoid too many fractions.

    6x -y/4 = -9
    Multiply both sides by 8,
    48x -2y = -72 -------------(i),
    Add that to the other equation, to eliminate the y's,
    3x +2y = -30
    --------------
    51x +0 = -102
    x = -102 / 51
    x = -2 -----------***
    Substitute that into the other equation,
    3(-2) +2y = -30
    -6 +2y = -30
    2y = -30 +6
    2y = -24
    y = -24/2
    y = -12 ------------***

    Check those in the 1st equation,
    6x -y/4 = -9
    6(-2) -(-12)/4 =? -9
    -12 +3 =? -9
    -9 =? -9
    Yes, so, Ok.
    Last edited by ticbol; October 8th 2005 at 10:26 PM.
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  3. #3
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    Thank you for the help.
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