已知4x-5y+z=7,6x-9y+z=11,则x+y+z的值为?

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/26 19:46:57
已知4x-5y+z=7,6x-9y+z=11,则x+y+z的值为?
xN0E%c+Dv>Eؙ"jS ! ׌/Il`e87k8ח> ߵ,='_$f!WsH]Y~lk$܎}W]F>CvM*  Vryزq[t`5O di;'݋R{ [hWBqԾ"!v<

已知4x-5y+z=7,6x-9y+z=11,则x+y+z的值为?
已知4x-5y+z=7,6x-9y+z=11,则x+y+z的值为?

已知4x-5y+z=7,6x-9y+z=11,则x+y+z的值为?
答:
4x-5y+z=7…………(1)
6x-9y+z=11…………(2)
(2)-(1)得:
2x-4y=4
x-2y=2
x=2y+2
代入(1)得:
8y+8-5y+z=7
3y=-z-1
所以:
x+y+z
=2y+2+y+z
=3y+z+2
=-z-1+z+2
=1

1. 两式相减得x=2+2y ,把它带入前式,得z=-1-3y 所以x+y+z=1