Definition of L'Hopital's rule
: a theorem in calculus: if at a given point two functions have an infinite limit or zero as a limit and are both differentiable in a neighborhood of this point then the limit of the quotient of the functions is equal to the limit of the quotient of their derivatives provided that this limit exists
Origin and Etymology of l'hopital's rule
Guillaume de l'Hôpital †1704 French mathematician
First Known Use: 1918
Seen and Heard
What made you want to look up L'Hopital's rule? Please tell us where you read or heard it (including the quote, if possible).