View more at http://www.MathTutorDVD.com. In this lesson, you will learn how to graph rational functions in algebra by calculating and graphing the vertical asymptotes and horizontal asymptotes of the function. The vertical asymptotes are located by setting the denominator of the function equal to zero and solving for the values of "x". The horizontal asymptotes are found by examining the function's behavior as x approaches infinity. Once we know the vertical and horizontal asymptotes, we can calculate a few points of the function in order to sketch the graph.