![cover image](https://wikiwandv2-19431.kxcdn.com/_next/image?url=https://upload.wikimedia.org/wikipedia/commons/thumb/3/3f/Schema_R%25C3%25A8gle_produit.png/640px-Schema_R%25C3%25A8gle_produit.png&w=640&q=50)
Product rule
Formula for the derivative of a product / From Wikipedia, the free encyclopedia
This article is about the derivative of a product. For the relation between derivatives of 3 dependent variables, see Triple product rule. For a counting principle in combinatorics, see Rule of product. For conditional probabilities, see Chain rule (probability).
In calculus, the product rule (or Leibniz rule[1] or Leibniz product rule) is a formula used to find the derivatives of products of two or more functions. For two functions, it may be stated in Lagrange's notation as or in Leibniz's notation as
![](http://upload.wikimedia.org/wikipedia/commons/thumb/3/3f/Schema_R%C3%A8gle_produit.png/640px-Schema_R%C3%A8gle_produit.png)
The rule may be extended or generalized to products of three or more functions, to a rule for higher-order derivatives of a product, and to other contexts.