Question

解三元一次方程 x+y-2z=1 3x+y+z=0 2x-y+3z=1

Answer 1

x+y-2z=1 (1)

3x+y+z=0 (2)

2x-y+3z=1 (3)

(2)-(1)

3x+z-x=2z=-1

2x+3z=-1 (4)

(1)+(3)

3x+z=2 (5)

(4)-(5)x3

2x-9x=-1-6

-7x=-7

x=1

3x+z=2

z=-1

x+y-2z=1

1+y+2=1

y=-2

所以

x=1 ,y=-2 ,z=-1

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