Question

解三元方程组,x+y—z=0,2x+y+z=7,x—3y+z=8

Answer 1

x+y-z=0 (1)

2x+y+z=7 (2)

x-3y+z=8 (3)

(1)+(2)

3x+2y=7 (4)

(1)+(3)

2x-2y=8 (5)

(4)+(5)

5x=15

x=3

y=(2x-8)/2=-1

z=x+y=2

综上 x=3 y=-1 z=2