9X-5Y+Z=-6 (1)
9X+Y+4Z=3 (2)
-9X+3Y-5Z=0 (3)
(2)-(1)
6Y+3Z=9
2Y+Z=3 (4)
(2)+(3)
4Y-Z=3 (5)
(4)+(5)
6Y=6
所以
Y=1
Z=3-2Y=1
X=(3-Y-4Z)/9=-2/9