x-2y+z=-1 (1)
{x+y+z=2 (2)
{x+2y+3z=-1 (3)
①+③得2x+4y=-2
①-②得-3y=-3 y=1
带入上一个方程为x=-3
然后再带入方程得z=6
2x+y-z=2 (1)
{x+2y-z=5 (2)
{x-y+2z=-7 (3)
①+③的3x+z=-5 x=-5-z/3④
②-③德3y-3z=12 y-z=4 y=z+4⑤
①-②得x-y=-3
-5-z-3z-12=-9
z=-2
x=-1
y=2
x-2y+z=-1 (1)
{x+y+z=2 (2)
{x+2y+3z=-1 (3)
①+③得2x+4y=-2
①-②得-3y=-3 y=1
带入上一个方程为x=-3
然后再带入方程得z=6
2x+y-z=2 (1)
{x+2y-z=5 (2)
{x-y+2z=-7 (3)
①+③的3x+z=-5 x=-5-z/3④
②-③德3y-3z=12 y-z=4 y=z+4⑤
①-②得x-y=-3
-5-z-3z-12=-9
z=-2
x=-1
y=2