(1)若两直线平行,则其斜率相等,即(1-m)/(m+1)=(2-0)/(1+5)
得m=1/2.
(2)若两直线垂直,则其斜率互为负倒数,即 [(1-m)/(m+1)]×[(2-0)/(1+5)]=-1
得m=-2