X+Y-Z=6 ①X-Y+2Z=-7 ②3X+2Y+Z=7 ③①搭做旅胡判+②,得 2x+z=-1 ④②×2+③,得 5x+5z=-7 ⑤知凳④×5-⑤,得 x=2/5把x代入④,得 z=-9/5把x,z代入①,得 y=19/5
x=2/5y=19/5z=-9/5
