Question

Solve each system by elimination.

-9x + 4y = 7
-2x-4y=-18

Answer 1

X=1

Explanation:

-9x + 4y = 7

-2x-4y=-18

Since the variables are opposites add -9x+-2x

and you get -11x 4y + -4y = 0 and -18 +7=11

-11x=-11 divide that by 11 and get 1

Answer 2

(1, 4 )

Explanation:

- 9x + 4y = 7 → (1)

- 2x - 4y = - 18 → 2)

add (1) and (2) term by term to eliminate y

- 11x + 0 = - 11

- 11x = - 11 ( divide both sides by - 11 )

x = 1

substitute x = 1 into either of the 2 equations and solve for y

substituting into (1)

- 9(1) + 4y = 7

- 9 + 4y = 7 ( add 9 to both sides )

4y = 16 ( divide both sides by 4 )

y = 4

solution is (1, 4 )