algebra

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Solveing using the addition method
-5x-9y=19
8x-7y=-9

  • algebra -

    1st times 8 ----> -40x - 72y = 152
    2nd times 5 ----> 40x - 35y = -45
    add them
    - 107y = 107
    y = -1
    back into 1st:
    -5x + 9 = 19
    -5x = 10
    x = -2

  • algebra -

    We can solve x or y, so I'll pick y. Let's get rid of x by multiplying the top equation by 8 and the bottom equation by 5:

    8(-5x - 9y = 19)
    5(8x - 7y = -9)

    -40x - 72y = 152
    40x - 35y = -45
    ---------------
    .... -107y = 107
    .........y = -1

    I'll let you take it from here to figure out the value of x. Check solutions with the original equations. It always helps to check your work!

    I hope this will help get you started.

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