i do see that there is vertical assymptote.please find below the reasoning
1> Vertical asymptotesThe line x = a is a vertical asymptote of the graph of the function y = ƒ(x) if at least one of the following statements is true:
a.lim x-> afor f(x) = + or - infinity
b.lim x-> -afor f(x) = + or - infinity.
2.keeping the first point in mind and applying L-Hospital's rule for f(x) it becomes (2x-9)/(2x-8).then put x=4 we get -1/0= -infinity
3.L-Hospital's rule;is a rule for converting an indeterminent form of functions (i.e 0/0,infinity/infinity,o^infinity,infinity^0,infinity-infinity......)into diterminent forms by differentiating the given function.