解方程组3x+2y+z=9 ,x+y+2z=0 ,2x+3y-z=11

问题描述:

解方程组3x+2y+z=9 ,x+y+2z=0 ,2x+3y-z=11


3x+2y+z=9 ①
x+y+2z=0 ②
2x+3y-z=11 ③
①×2得:6x+4y+2z=18 ④
④-②得:5x+3y=18 ⑤
①+③得:5x+5y=20 ⑥
⑥-⑤得:2y=2
∴y=1,将y=1代入⑥得:x=3
∴z=-2
∴x=3,y=1,z=-2