Question

Solve this system of equations using the Substitution method. All work and a brief phrase/sentence explaining what you're doing needs to be shown for each step for full credit. Write final answer as a coordinate point.

12x + 4y = -8
y = 2x + 3

Answer 1

(- 1, 1 )

Explanation:

12x + 4y = - 8 → (1)

y = 2x + 3 → (2)

substitute y = 2x + 3 into (1)

12x + 4(2x + 3) = - 8 ← distribute parenthesis on left side and simplify

12x + 8x + 12 = - 8

20x + 12 = - 8 ( subtract 12 from both sides )

20x = - 20 (divide both sides by 20 )

x = - 1

substitute x = - 1 into (2) and solve for y

y = 2(- 1) + 3 = - 2 + 3 = 1

solution is (- 1, 1 )