Vertical asymptotes: set the denominator equal to 0
Vertical asymptotes: factor the numerator and denominator first
Vertical asymptotes: cancel any common factors
Vertical asymptotes: the remaining denominator zeros give vertical asymptotes
Vertical asymptotes: if a factor cancels, it is a hole, not a vertical asymptote
Horizontal asymptotes: compare the degrees of the numerator and denominator
Horizontal asymptotes: if numerator degree is less than denominator degree, y = 0
Horizontal asymptotes: if numerator degree equals denominator degree, y = ratio of leading coefficients
Horizontal asymptotes: if numerator degree is greater than denominator degree, there is no horizontal asymptote
Horizontal asymptotes: if numerator degree is exactly 1 more than denominator degree, look for a slant asymptote instead