## Precalculus (6th Edition) Blitzer

For a rational function, say $F\left( x \right)=\frac{P\left( x \right)}{Q\left( x \right)}$ , the vertical asymptote depends on the denominator term. Equate $Q\left( x \right)$ to 0, and calculate asymptotes based on the values of x obtained. At the points where $Q\left( x \right)=0$ the rational function is not defined and hence a vertical asymptote can never cross the graph of the function. Also, an asymptote is defined as a line which a function approaches, but never meets. Hence, a rational function cannot ever cross the asymptote. Therefore, the given statement is true.