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28x-3y+2z=297x-y-z=-1-x+2y-z=0
题目详情
28x-3y+2z=29 7x-y-z=-1 -x+2y-z=0
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答案和解析
(1)+(2)×2得
42x-5y=27 (4)
(2)-(3)得
8x-3y=-1 (5)
(4)×3-(5)×5得
86x=86
∴ x=1
把x=1代入(5)得
8-3y=-1
∴y=3
把x=1,y=3代入(3)得
-1+6-z=0
∴z=5
∴方程组的解是
x=1
y=3
z=5
42x-5y=27 (4)
(2)-(3)得
8x-3y=-1 (5)
(4)×3-(5)×5得
86x=86
∴ x=1
把x=1代入(5)得
8-3y=-1
∴y=3
把x=1,y=3代入(3)得
-1+6-z=0
∴z=5
∴方程组的解是
x=1
y=3
z=5
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