2x+3y-4z=-7x-4y 2y+3z-----=------=23 2

2x+3y-4z=-7x-4y 2y+3z-----=------=23 2
2x+3y-4z=-7
x-4y 2y+3z
-----=------=2
3 2

2x+3y-4z=-7x-4y 2y+3z-----=------=23 2
(x-4y)/3=(2y+3z)/2=2
所以x-4y=6 (1)
2y+3z=4 (2)
2x+3y-4z=-7 (3)
由(1)
x=4y+6 (4)
代入(3)
8y+12+3y-4z=-7
11y-4z=-19 (5)
(2)*4+(5)*3
8y+33y=16-57
41y=-41
y=-1
z=(11y+19)/4=2
x=4y+6=2