5x+2y-3z=2 ①
x+2y+z=6 ②
7x-2y-4z=26 ③
①-②得：x - z = -1 ④
②+③得：8x-3z=32 ⑤
④*2-⑤得：-8z+3z=-8-32
z = 8 ⑥
将⑥代入④得：x= - 7 ⑦
再将⑥⑦代入①得：y= - 9/2