3.A. L'Hospital's Rule

First important thing about L'Hospital's rule is how to pronounce it. "L'Hospital" is pronounced "low pea tall". The rule uses derivatives to help evaluate limits involving indeterminate forms.

Application (or repeated application) of the rule often converts an indeterminate form to a simpler expression that can be evaluated by substitution. 

L'Hospital's rule states that for functions f and g which are differentiable on an open interval I except possibly at a point c contained in I, if

  • Key Terms
    • indeterminate form
    • L'Hospital's Rule

Essential Questions
  • How can L'Hospital's Rule be used to evaluate limits?