1.3x-y=4 ①
5 x+2y+z=4 ②
2x+3y-2z=-2 ③
由①得：y=3x-4 ④
②*2+③得12x+7y=6⑤
④代入⑤得：x=34/33 ⑥
⑥代入④得：y=-10/11⑦
⑥⑦代入②得：z=2/3
2.x-4y+z=3 ①
2x+y-z=18 ②
x-y-z=7 ③
①+②得：x+y=7 ④
②-③得：x+2y=11⑤
⑤-④得：y=4 ⑥
⑥代入④得：x=3⑦
⑥⑦代入③得：z=-8