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Math Help - solve please

  1. #1
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    solve please

    using the substitution method

    5x +7y = -1
    -6x + y = 20
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  2. #2
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    What are you having trouble with, just eliminate one of the variables and solve for the other.
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  3. #3
    A riddle wrapped in an enigma
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    Quote Originally Posted by mathdummy22 View Post
    using the substitution method

    5x +7y = -1
    -6x + y = 20
    Solve the second equation for y.

    y=6x+20

    Substitute 6x+20 for y in the first equation and solve for x.

    Once you have x, you can use either equation to find y.
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  4. #4
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    i get x = -139/47 and y= 106/47..... I have no clue what Im doing wrong
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  5. #5
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    5x +7y = -1
    -6x + y = 20

    y = 6x+20
    7y = 42x +140
    5x+42X+140 =-1 Here is where you screw up.
    47x = -141
    x = -3
    y = 2 by substitution.
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  6. #6
    A riddle wrapped in an enigma
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    Solve the second equation for y.

    y=6x+20

    Substitute back into 1st equation:

    5x+7(6x+20)=-1

    5x+42x+140=-1

    47x=-141

    x=-3

    Now solve for y using y=6x+20
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  7. #7
    A riddle wrapped in an enigma
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    Quote Originally Posted by terr13 View Post
    5x+42X+140 =-1 Here is where you screw up.
    When I screw something up, I always try to screw it back down.
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