1. The document discusses the concept of derivatives and average rate of change in calculus. It provides examples of taking the derivative of several common functions like x^n, sin(x), cos(x), and tan(x). 2. Examples are given of calculating the derivative of each function by taking the limit as h approaches 0 of the difference quotient (f(x+h)-f(x))/h. 3. For each example, the document shows that the derivative is equal to the known formula such as nx^n-1 for f(x)=x^n, cos(x) for f(x)=sin(x), etc.