x+y+z=14
问题描述：
x+y+z=14
x-y+z=0
7y-(x+y)=2
答
x+y+z=14 (1)
x-y+z=0 (2)
7y-(x+y)=2 (3)
(1)-(2),得:2y=14
y=7
代入(3)得,49-x-7=2
x=40
将x,y代入(1),得:z=-33