X+Y=Z 2X-3Y+2Z=5 X+3Y-Z=3X+Y=Z2X-3Y+2Z=3X+3Y-Z=3

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X+Y=Z2X-3Y+2Z=5X+3Y-Z=3X+Y=Z2X-3Y+2Z=3X+3Y-Z=3X+Y=Z2X-3Y+2Z=5X+3Y-Z=3X+Y=Z2X-3Y+2Z=3X+3Y-Z=3X+Y=Z2X-

X+Y=Z 2X-3Y+2Z=5 X+3Y-Z=3X+Y=Z2X-3Y+2Z=3X+3Y-Z=3
X+Y=Z 2X-3Y+2Z=5 X+3Y-Z=3
X+Y=Z
2X-3Y+2Z=3
X+3Y-Z=3

X+Y=Z 2X-3Y+2Z=5 X+3Y-Z=3X+Y=Z2X-3Y+2Z=3X+3Y-Z=3
X+Y-Z=0 (1)
2X-3Y+2Z=3 (2)
X+3Y-Z=3 (3)
(3)-(1)得
Y=3/2 (4)
(3)*2+(2)得
4X+3Y=9 (5)
把(4)代入(5)得
X=9/8
把X,Y 代入(1)得
Z=21/8
解多元方程组关键是要消元.加减消元和代入消元两种方法均可

x=1.125
y=1.5
z=2.625

到底问什么,求未知数吗

X+Y=Z①
2X-3Y+2Z=3②
X+3Y-Z=3③
③-①得Y=3/2④
③+②,得3X+Z=6,Z=6-3X⑤
将④⑤,代入①得X=9/8,Z=21/8