Write the system of linear equations in the form Ax=b. Then use Ga −3x 1
​ −x 2
​ +x 3
​ =−4 −3x 1
​ −x 2
​ +x 3
​ 2x 1
​ +4x 2
​ −5x 3
​ =15
x 1
​ −2x 2
​ +3x 3
​ ​ =−4
=−9
​ ⎦
⎤
​ ⎣
⎡
​ x 1
​ x 2
​ x 3
​ ​ ⎦
⎤
​ = ⎣
⎡
​ −4
15
−9
​ ⎦
⎤
​