Question

Solve this system of linear equations. Separate

the x- and y-values with a comma.
7x + 9y = 10
-2x + 6y = -20

Answer 1

(4, - 2 )

Explanation:

Given the 2 equations

7x + 9y = 10 → (1)

- 2x + 6y = - 20 → (2)

Multiplying (1) by 2 and (2) by 7 and adding will eliminate the x term

14x + 18y = 20 → (3)

- 14x + 42y = - 140 → (4)

Add (3) and (4) term by term

(14x - 14x) + (18y + 42y) = (20 - 140), that is

60y = - 120 ( divide both sides by 60 )

y = - 2

Substitute y = - 2 into either of the 2 equations and solve for x

Substituting in (1)

7x + 9(- 2) = 10

7x - 18 = 10 ( add 18 to both sides )

7x = 28 ( divide both sides by 7 )

x = 4

Solution is (4, - 2 )