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5 votes
−3x−9y=18
4x+3y=12


User Carly
by
5.1k points

1 Answer

2 votes

Answer:

x = 6 , y = -4

Explanation:

Solve the following system:

{-9 y - 3 x = 18 | (equation 1)

3 y + 4 x = 12 | (equation 2)

Swap equation 1 with equation 2:

{4 x + 3 y = 12 | (equation 1)

-(3 x) - 9 y = 18 | (equation 2)

Add 3/4 × (equation 1) to equation 2:

{4 x + 3 y = 12 | (equation 1)

0 x - (27 y)/4 = 27 | (equation 2)

Multiply equation 2 by 4/27:

{4 x + 3 y = 12 | (equation 1)

0 x - y = 4 | (equation 2)

Multiply equation 2 by -1:

{4 x + 3 y = 12 | (equation 1)

0 x+y = -4 | (equation 2)

Subtract 3 × (equation 2) from equation 1:

{4 x+0 y = 24 | (equation 1)

0 x+y = -4 | (equation 2)

Divide equation 1 by 4:

{x+0 y = 6 | (equation 1)

0 x+y = -4 | (equation 2)

Collect results:

Answer: {x = 6 , y = -4