Question

Solve the system of linear equations by elimination. Show your work

2x-y=-3
4x + 3y = -21

Answer 1

x = -3, y = -3

Explanation:

Solve the following system:

{-y + 2 x = -3 | (equation 1)

3 y + 4 x = -21 | (equation 2)

Swap equation 1 with equation 2:

{4 x + 3 y = -21 | (equation 1)

2 x - y = -3 | (equation 2)

Subtract 1/2 × (equation 1) from equation 2:

{4 x + 3 y = -21 | (equation 1)

0 x - (5 y)/2 = 15/2 | (equation 2)

Multiply equation 2 by 2/5:

{4 x + 3 y = -21 | (equation 1)

0 x - y = 3 | (equation 2)

Multiply equation 2 by -1:

{4 x + 3 y = -21 | (equation 1)

0 x+y = -3 | (equation 2)

Subtract 3 × (equation 2) from equation 1:

{4 x+0 y = -12 | (equation 1)

0 x+y = -3 | (equation 2)

Divide equation 1 by 4:

{x+0 y = -3 | (equation 1)

0 x+y = -3 | (equation 2)

Collect results:

Answer: x = -3, y = -3