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Solve equation by elimination:

2x + y = - 1

6x + y = - 21

+1
Answers (2)
  1. 17 May, 06:30
    0
    Solve for y

    2x+y=-1

    y=-2x-1

    Sub y = - 2x-1 into an equation and solve for x

    6x-2x-1=-21

    4x-1=-21

    4x=-20

    x=-5

    Sub - 5 for x in either equation

    2 (-5) + y=-1

    -10 + y=-1

    y=9

    Check answer by substituting both solutions

    6 (-5) + 9=-21

    -30+9=-21

    -21=-21

    2 (-5) + 9=-1

    -10+9=-1

    -1=-1

    x=-5, y=9
  2. 17 May, 06:47
    0
    Change the sign on the first one, making it - 2x - y = 1

    Then combine the terms you have,

    -2x-y=1

    and

    6x+y=-21

    And this will give you

    4x=20

    Then solve that equation for x by dividing both sides by 4, giving you x=4

    Then plug 5 into x's place in either of the original equations.

    This is if you use the first equation

    2 (5) + y=-1

    Solve for y by simplifying

    10+y=-1

    Then subtract 10 from both sides

    y=-11.

    The final answer is x=5 and y=-11
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