Original
Notice that in this previous example, there was a vertical asymptote at {{MATH_115}}, even though the number {{MATH_116}} was not in the domain of the function {{MATH_117}}.
Vertical asymptotes are defined in terms of limits. The important point is that we can {{CMD_118}}approach{{CMD_119}} the number {{MATH_120}} from within the domain of {{MATH_121}}.