math problem

two lines do not intersect
therefore they are parallel to each other

slope of line 2x-y+1=0
= -a/b = 2
therefore the slope of line ax+3y-1=0 is also 2

-a/3 = 2
therefore a = -6

if the lines are parell then

2/-1 = a/3

hence a=-6

若兩線不相交,則兩條線斜率必定相同
so,
2/1=-a/3
a=-6

if the lines are parell then
2/-1 = a/3
hence a=-6