Knowing if a graph has a Horizontal Asymptote

1. You know a graph has a horizontal asymptote by comparing the degrees of the numerator and denominator. Their are three cases : when their is a bigger degree on top, if the degrees are the same, or if their is a bigger degree on bottom. When the degree is bigger on bottom, the asymptote is y=0. When the degrees are the same, the asymptote is the ratio of the coefficients. When the degree is bigger on top, their is no horizontal asymptote.