x+y+2z=0 2X-y+z=1 x+2y-3z=5
问题描述：
x+y+2z=0 2X-y+z=1 x+2y-3z=5
答
x+y+2z=0 2X-y+z=1 x+2y-3z=5
x+y+2z=0加上2X-y+z=1得到3x+3z=1
(2X-y+z=1)*2加上x+2y-3z=5得到5x-z=7
根据二元一次方程求得x=11/9 z=-8/9
代入任何等式求得
y=5/9