Question

2x+y=-2

x+y=5
the y coordinate of the solution to the system shown is___?

A. 12
B. -12
C. -7
D. 7

Answer 1

A

given the 2 equations

2x + y = - 2 → (1)

x + y = 5 → (2)

subtract (2) from (1) term by term to eliminate y

(2x - x ) + (y - y ) = (- 2 - 5 )

x + 0 = - 7 ⇒ x = - 7

substitute x = - 7 in either of the 2 equations and solve for y

(2) : - 7 + y = 5 ( add 7 to both sides )

y = 5 + 7 = 12 → A