Finding vertical asymptotes...

  • factor everything and reduce
  • if the denominator just goes away, it's a hole, not an asymptote
  • if the denominator is 0, the x value that made it so is the vertical asymptote

Finding horizontal asymptotes...

The algebra II way:

Where

  • n is the degree of the numerator
  • m is the dgree of the denominator

If

  • n < m, horizontal asymptote -> y=0
  • n = m, horizontal asymptote -> ratio of leading coefficients
  • n > m, horizontal asymptote -> no horizontal asymptote

The (later) calculus way

  • find the largest term in the denominator
  • divide numerator and denominator by that largest term
  • evalate limit of each as x -> ∞
  • if evalation yields a constant, then y = that constant is the horizontal asymptote
  • if not a constant, there are no horizontal asymptotes