The document introduces the quotient rule for taking the derivative of functions that are divided. Specifically, it states that if h(x) is defined as u(x)/v(x), then the quotient rule says that h'(x) is equal to (v(x)u'(x) - u(x)v'(x))/(v(x))^2. This rule, which rearranges the fraction and applies the product rule, was developed by Maria Gaetana Agnesi in her 1748 textbook as a way to help her brothers learn algebra. It then provides two examples of using the quotient rule to find the gradient function.