已知3x+7y+4z=35,x+5y+2z=40,则x+y+z=_.
问题描述:
已知3x+7y+4z=35,x+5y+2z=40,则x+y+z=______.
答
将两式组成方程组得
,
3x+7y+4z=35
①
x+5y+2z=40
②
①-②得,2x+2y+2z=-5,
∴x+y+z=-
.5 2
故本题答案为:-
.5 2