Question

解三元一次方程组2x-y+2z=8,y+2z=-2,3x+y-4z=1

Answer 1

2x-y+2z=8(1)

y+2z=-2(2)

3x+y-4z=1(3)

(1)+(2)

2x+4z=6

x+2z=3(4)

(3)-(2)

3x-6z=3

x-2z=1(5)

(4)+(5)

2x=4

x=2

代入(4)

2+2z=3

z=1/2

代入（2）

y+1=-2

y=-3

所以

x=2,y=-3,z=1/2