3x-y+z=3 (1)
2x+y-3z=11 (2)
x+y+z=12 (3)
(1)+(2)
5x-2z=14 (4)
(1)+(3)
4x+2z=15 (5)
(4)+(5)
9x=29
所以
x=29/9
z=(5x-14)/2=19/18
y=3x+z-3=139/18
3x-y+z=3 (1)
2x+y-3z=11 (2)
x+y+z=12 (3)
(1)+(2)
5x-2z=14 (4)
(1)+(3)
4x+2z=15 (5)
(4)+(5)
9x=29
所以
x=29/9
z=(5x-14)/2=19/18
y=3x+z-3=139/18