Question

三元一次方程组 {x-2y=-9 y-z=2 2z+x=47 怎么解

Answer 1

x-2y=-9 (1)

y-z=2 (2)

2z+x=47 (3)

(3)-(1)

2z+2y=56

y+z=28 (4)

(2)+(4)

2y=30

所以

y=15

x=2y-9=21

z=y-2=13