Question

Which of the following ordered pairs is a solution of the given system of linear equations?

Answer 1

4x + 3y = -2
2x - 2y = -8....multiply by -2
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4x + 3y = -2
-4x + 4y = 16 (result of multiplying by -2)
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7y = 14
y = 14/7
y = 2

2x - 2y = -8
2x - 2(2) = -8
2x - 4 = -8
2x = -8 + 4
2x = -4
x = -4/2
x = -2

solution is (-2,2)

Answer 2

4x + 3y = - 2 (a)
2x - 2y =  - 8 (b) Solve by elimination

Multiply (b) times (-2) → - 2[(2x - 2y) = - 8] ;  - 4x + 4y = +16 (c)
Add (a) to (c):
  4x + 3y = -2
- 4x + 4y = 16
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0x + 7 y  = 14 and y = 14/2 = 2. Now substitute y by 2 in either (a) or (b) and you will find x = - 2

So the solutions are x= - 2 & y=2 (answer C)