2)

For vertical asymptote:

make the denominator equal to zero

so you'll have: bx-1=0

now solve for x, x=1/b

now make x=1/2

so, 1/b=1/2

therefore b=2

now for the horizontal asymptotes, make x go to infinity on the numerator and denominator, so you will end up pretty much with:

ax/bx, x's go away and now you have:

a/b, you know b=2, so: a/2 must be equal to 1/2

so a=1

Someone please confirm this.