Hi Semen
exp = (2 x^2 - 9)/Sqrt[x^2 - 1];
asymptotes = ResourceFunction["Asymptotes"][exp, x, y]
(* <|"Vertical" -> {{y -> -∞, x -> ±1}},
"Oblique" -> {{y -> -2 x, x -> -∞}, {y -> 2 x, x -> ∞}}|> *)
If you have to do this for many plots, I would write some code to generate line endpoints from asymptotes
. Here I just did it manually
epilog = {Dashed, Darker[Green], InfiniteLine[{{-1, -1}, {-1, 1}}],
InfiniteLine[{{1, -1}, {1, 1}}], Red, InfiniteLine[{{-1, -2}, {0, 0}}]}
Plot[exp, {x, -13, 13}, AxesLabel -> {"X", "Y"}, Epilog -> epilog]
