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DJBreezy

  • one year ago

Name the y value of the solution to the system of equations. Use substitution: -4x + y = 6 -5x - y = 21

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  1. Jamierox4ev3r
    • one year ago
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    you might have to set the two to equal each other -4x+y=6 +4x +4x --------- y=4x+6 then -5x-y=21 +5x +5x --------- -y=5x+21 y=-5x-21

  2. Jamierox4ev3r
    • one year ago
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    then you could do this: -5x-21=4x+6 since each end equals y. Then solve for x. Once you solve for x, plug the x value into one of the equations and solve for y ^^

  3. DJBreezy
    • one year ago
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    x=−3

  4. Jamierox4ev3r
    • one year ago
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    @DJBreezy does this make sense so far?

  5. Jamierox4ev3r
    • one year ago
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    -5x-21=4x+6 +5x +5x ---------- -21=9x+6 -6 -6 --------- -27=9x /9 /9 ------ x=-3 \(\color{green}\checkmark\) that's right :)

  6. Jamierox4ev3r
    • one year ago
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    now we solve for y -4(-3)+y=6 12+y=6 -12 -12 ------- y=-6

  7. Jamierox4ev3r
    • one year ago
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    you can also check with the other equation -5(-3)-y=21 15-y=21 -15 -15 ------- -y=6 y=-6

  8. Jamierox4ev3r
    • one year ago
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    both equations yield y=-6 therefore, the value of y is -6. Do you understand?

  9. DJBreezy
    • one year ago
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    so the answer is -6??

  10. DJBreezy
    • one year ago
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    yes and thx

  11. Jamierox4ev3r
    • one year ago
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    no problem :)

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