(1)若l1,l2相交,
1/(m-2)≠m/3
m≠1,3
(2)若l1,l2平行,
1/(m-2)＝m/3≠6/(2m)
解得m=-1
(3)若l1,l2重合,
1/(m-2)＝m/3＝6/(2m)
解得m=3
注：l1:a1x+b1y+c1=0 l2:a2x+b2y+c2=0 (a2,b2,c2≠0)
若l1,l2平行,a1/a2＝b1/b2≠c1/c2
若l1,l2重合,a1/a2＝b1/b2＝c1/c2
若l1,l2相交,a1/a2≠b1/b2