已知x、y、z满足{3x+7y+z=5 ,求x+y+z的值 {4x+10y+z=3

题目

已知x、y、z满足{3x+7y+z=5 ,求x+y+z的值 {4x+10y+z=3

答案

3x+7y+z=5.(1)
4x+10y+z=3.(2)
(1)*3-(2)*2有
9x+21y+3z-(8x+20y+2z)=5*3-3*2
x+y+z=15-6
x+y+z=9