12y+9z=x,6(y+1/4)+9z=x,y+z=x
问题描述：
12y+9z=x,6(y+1/4)+9z=x,y+z=x
答
将y+z=x代入前两式,有
12y+9z=y+z,即 11y+8z=0 ----(1)
6(y+1/4)+9z=y+z,即 5y+8z+3/2=0 ----(2)
(1)-(2)得6y-3/2=0,即 y=1/4,代入(1)得z=-11/32,x=y+z=-3/32