l'Hôpital's rule


l'Hôpital's rule

[lō·pē·tälz ‚rūl] (mathematics) A rule useful in evaluating indeterminate forms: if both the functions ƒ(x) and g (x) and all their derivatives up to order (n- 1) vanish at x = a, but the n th derivatives both do not vanish or both become infinite at x = a, then ƒ(n)denoting the n th derivative.