Question

若x=-1,y=-8与x=2,y=-2是方程mx+ny=6的两个解,求m+2n的值

Answer 1

-m-8n=6,即：m+8n=-6 .(1)

2m-2n=6,即：n=m-3 .(2)

m+8(m-3)=-6

9m-24=-6

9m=18

m=2

n=m-3=-1

m+2n=2-2=0