如圖:()
A.AB.BC.CD.D
A.X+2y-z-6=0 B.2x-Y=0 C.Y+2z=0 D.x+z=0
A.x+y+4z-3=0B.2x+y+z-3=0C.x+2y+z-19=0D.x+2y+4z-9=0