解方程组x-y-z=5 2x+2y-z=15 2x+3y=18

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解方程组x-y-z=52x+2y-z=152x+3y=18解方程组x-y-z=52x+2y-z=152x+3y=18解方程组x-y-z=52x+2y-z=152x+3y=18x-y-z=5.①2x+2

解方程组x-y-z=5 2x+2y-z=15 2x+3y=18
解方程组x-y-z=5 2x+2y-z=15 2x+3y=18

解方程组x-y-z=5 2x+2y-z=15 2x+3y=18
x-y-z=5.①
2x+2y-z=15.②
2x+3y=18.③
②-①得
2x+2y-z-(x-y-z)=15-5
x+3y=10.④
③-④得
2x+3y-(x+3y)=18-10
x=8
将x=8代入④式得
y=2/3
将X,Y代入①式,得
z=7/3

2x-2y-2z=10 (1)
2x+2y-z=15 (2)
(2)-(1)
4y+z=5
2x+3y=18 (3)
(3)-(2)
y+z=3
3y=2
y=2/3
z=7/3
x=8

三元一次......
基础的不能在基础了.
X=8、Y=2/3、Z=7/3

2、x+y-z=6 x-3y+2z=1 3x+2y-z=4 3、x+y=3 y+z=5 x+z=6②+③d等于2x+y=0 等于然后解新方程组 x=-1 y=2 带入①得,z=-2