How do you solve $2x + y = -1$ and $x - 2y = 7$ ?

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Answer 1 · 2015-08-17T15:26:52

x = 1 ; y = - 3

2x + y= −1 ___(1)
x − 2y = 7 ____(2) $xx$ 2
2x - 4y = 14 ------------------------(3)

Subtract (3) from (1)

2x + y= −1
2x - 4y = 14

  5y = - 15

    y = -3

Substitute y = - 3 in equation (1)

2x + ( - 3) = - 1

2x - 3 = - 1 Multiply both sides by 5
10x - 15 = - 5
10x = - 5 + 15 = 10
x = $(10)/10$ = 1
x = 1

How do you solve 2x + y = -12x + y = -1 and x - 2y = 7x - 2y = 7?