x+2y+3z=10 5x+4y+3z=8 x+y+z=
问题描述：
x+2y+3z=10 5x+4y+3z=8 x+y+z=
答
答案：3
另A=x+y+z,另B=y+2Z分别带入上述两式
得：
x+2y+3z=10 => x+y+z +y+2z=10 => A+B=10 ----(3)
5x+4y+3z=8 => 5(x+y+z)-(y+2z)=8 => 5A-B=8 ----(4)
(3)式加(4)式,得：6A=18 => A=x+y+z=3