If the graph of a rational function R has the vertical asymptote x=4 the factor x-4 must be present in the denominator of R

"We say that f (x) is in lowest terms if P (x) and Q (x) have no common factors. 1 ... The rational functionf (x) = P (x) / Q (x) in lowest terms has horizontal asymptote y = 0 if the degree of the numerator, P (x), is less than the degree of denominator, Q (x) ... For example, just because x = a is a simple root of Q (x) does not mean that it ..."