x+y+z=0(1)
4x+2y+z=3(2)
9x+3y+z=6(3)
(2)-(1) 3x+y=3(4)
(3)-(1) 8x+2y=6(5)
(4)*2 6x+2y=6(6)
(5)-(6) 2x=0
x=0
y=3
z=-3