x-2y-3=0 (1),
5x+4y+8=0 (2)
(1)乘以2,
2x-4y-6=0(3)
(2)+(3),得
7x+2=0,得x=-2/7,
代入(1),得y=-23/14
x-2y+3z=0 (1),
3x+2y+5z=12 (2),
2x-4y-z=7 (3)
(1)式乘以-1,得
-x+2y-3z=0 (4)
(2)+(3)+(4),得4x+z=19,得z=19-4x,代入(1),(2)
x-2y+3(19-4x)=0 (5),
3x+2y+5(19-4x)=12 (6),
(5)+(6),得x=5,
代入z=19-4x,得z=-1,
x=5,z=-1代入(1),得y=1