Question 1119595
Line L has an equation {{{x+2y=0}}}.


Both lines contain point  (2a, a+1).


{{{system(2x-y=b,x+2y=0)}}}


{{{system(2*2a-a-1=b,2a+2a+2=0)}}}


{{{system(4a-a-1=b,4a+2=0)}}}


{{{system(3a-1=b,4a+2=0)}}}


-

{{{12a-4=4b,12a+6=0}}}


{{{-10=4b}}}


{{{highlight(b=-5/2)}}}