Inclined asymptote can be found by calculating the limit of cos(5*x)*cos(x), divided by x at x->+oo and x ->-oo
x→−∞lim(xcos(x)cos(5x))=0Let's take the limitso,
inclined coincides with the horizontal asymptote on the right
x→∞lim(xcos(x)cos(5x))=0Let's take the limitso,
inclined coincides with the horizontal asymptote on the left