Question

已知两直线L1:4x+(3+m)y+3m-5=0,L2:(5+m)x+2y-8=0,(1)当M为何值时,L1//L2;

Answer 1

两直线平行,k相等4=5+m

m=-1

两直线垂直,k互为负倒数-4分之1=5+m

m=-4分之21