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1、3x+2y-z=1x-2y+2z=55x-2y+5z=11
题目详情
1、 3x+2y-z=1
x-2y+2z=5
5x-2y+5z=11
x-2y+2z=5
5x-2y+5z=11
▼优质解答
答案和解析
3x+2y-z=1 (1)
x-2y+2z=5 (2)
5x-2y+5z=11 (3)
(1)+(2)得4X+Z=6,即Z=6-4X (4)
(1)+(3)得8X+4Z=12,即2X+Z=3 (5)
将(4)代入(5)得2X+6-4X=3,得X=3/2 (6)
将(6)代入(4)得Z=6-4X(3/2)=0 (7)
将(6)(7)代入(1)得3X(3/2)+2Y+0=1,得Y=-7/4
x-2y+2z=5 (2)
5x-2y+5z=11 (3)
(1)+(2)得4X+Z=6,即Z=6-4X (4)
(1)+(3)得8X+4Z=12,即2X+Z=3 (5)
将(4)代入(5)得2X+6-4X=3,得X=3/2 (6)
将(6)代入(4)得Z=6-4X(3/2)=0 (7)
将(6)(7)代入(1)得3X(3/2)+2Y+0=1,得Y=-7/4
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