L'Hôpital's rule

When a limit of a quotient of two functions gives an indeterminate form such as 0/0 or infinity/infinity, the limit of the quotient equals the limit of the quotient of their derivatives. It is used to evaluate such limits when direct substitution fails.

\lim_{x \to a} \frac{f(x)}{g(x)} = \lim_{x \to a} \frac{f'(x)}{g'(x)}

What the symbols mean

numerator function
denominator function, with g(x) nonzero near a
derivative of f with respect to x
derivative of g with respect to x
point (or infinity) that x approaches

About this formula

  • FieldMathematics
  • TopicLimits and derivatives
  • LevelUniversity
  • Also calledBernoulli-L'Hôpital's rule, limit of a fraction using derivatives, indeterminate form 0/0 limit, derivative rule for limits, L'Hospital's rule
  • SourceWikidata Q190557

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