方程组 (1) x+2y-3z=12 x-3y+2z= - 13 x-y-z=0 (2) x+ y=z 5x-y+z=18 2x+5y+3z= -1
问题描述：
方程组 (1) x+2y-3z=12 x-3y+2z= - 13 x-y-z=0 (2) x+ y=z 5x-y+z=18 2x+5y+3z= -1
答
(1) x+2y-3z=12
x-3y+2z=-13
x-y-z=0
2y-2z=10 -2y+3z=-13
z=-3 y=2 x=-1
(2) x+ y-z =0
5x-y+z=18
2x+5y+3z= -1
6x=18
x=3
y-z=-3 3y-3z=-9
5y+3z=-7
y=-2 z=1 x=3