x+y+z=0 ①
4x+2y+z=3 ②
9x+3y+z=6 ③
②-①得3x+y=3 ④,
③-②得5x+y=3 ⑤,
⑤-④得x=0,
代入④得y=3,代入①得z=-3
∴x=0
y=3
z=-3