Question

m为何值时,关于x,y的方程组 2x-y=2m-1 -x+3y+m满足x+2y小于等于0

Answer 1

2x-y=2m-1 .(1)

-x+3y=m.(2)

(1)+(2)*2得

5y=4m-1

y=(4m-1)/5

代入(2)得

2x-(4m-1)/5=2m-1

10x-4m+1=10m-5

10x=14m-4

x=(7m-2)/5

x+2y

=(15m-4)/5≤0

15m-4≤0

15m≤4

m≤4/15