Rational Functions have vertical and horizontal "imaginary lines where a graph come close to but doesn't usually make contact or cross it" [aka] asymptotes. A vertical asymptote occur when x-values are undefined because they make the denominator equal to zero (0). In order to find the vertical asymptote, you must:

1. Factor the denominator (if possible).
2. Set each factor to 0.
3. Solve

X = # will be the line of the vertical asymptote, represented as a vertical line. There may be one or more of these vertical asymptotes depending on the equation you're given.