(m^2-2m-3)x+(2m^2+m-1)y-2m+6=0
(2m^2+m-1)y=-(m^2-2m-3)x+2m-6
两边除以(2m^2+m-1),
k=-(m^2-2m-3)/(2m^2+m-1)=1
3m^2-m-4=0
m=-1,m=4/3
m=1,y系数为0,k=1不成立
所以m=4/3