Question

x-y-z=1 2x+y-3z=4 3x-2y-z=-1

Answer 1

x-y-z=1 ①
2x+y-3z=4 ②
3x-2y-z=-1 ③
解：③-①，得：2x-y=-2 ④
②-③×3，得：
-x-y =1 ⑤
由④与⑤得x =-1
把x＝-1代入⑤，得y＝0
把x＝-1 y＝0代入①
得：z＝-2
∴原方程组的解是x＝-1 y＝0 z＝-2

Answer 2

x-y-z=1 (1)
2x+y-3z=4 (2)
3x-2y-z=-1 (3)
(1)×3-(2)得
x-4y=-1 (4)
(3)-(1)得
2x-y=-2 (5)
(5)-(4)×2得
7y=0
∴y=0
把y=0代入(4)得
x=-1
把x=-1,y=0代入(1)得
z=-2
∴x=-1
y=0
z=-2

Answer 3

x-y-z=1.......① ⑥ ⑦
2x+y-3z=4..②
3x-2y-z=-1.③
③-① 2x-y=-2④
③*3-② 7x-7y=-7,x-y=-1⑤
④-⑤ x=-1, y=0....代入① z=-2
x=-1
y=0
z=-2