{x-y-z=-1 {3x+5y +7z=11 {4x-y+2z=-1 求X,Y,

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{x-y-z=-1 {3x+5y +7z=11 {4x-y+2z=-1 求X,Y,
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{x-y-z=-1 {3x+5y +7z=11 {4x-y+2z=-1 求X,Y,
{x-y-z=-1 {3x+5y +7z=11 {4x-y+2z=-1 求X,Y,

{x-y-z=-1 {3x+5y +7z=11 {4x-y+2z=-1 求X,Y,
x-y-z=-1(1)
3x+5y+7z=11(2)
4x-y+2z=-1(3)
(1)*7 7x-7y-7z=-7(4)
(2)+(4) 10x-2y=4
5x-y=2
(1)*2 2x-2y-2z=-2(5)
(3)+(5) 6x-3y=-3
2x-y=-1(6)
5x-y=2(7)
(7)-(6) 3x=3
x=1
y=2x+1=3
z=x-y+1=1-3+1=-1
x=1,y=3,z=-1

x-y-z=-1 (1)
3x+5y +7z=11 (2)
4x-y+2z=-1 (3)
(1)×2+(3):
6X-3Y=-3 (4)
(1)×7+(2):
10x-2y=4 (5)
(4)×2-(5)×3
-18x=-18 ,
∴x=1, y=3,z=-1

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