Suppose that f is a function given as f(x). We will compute the derivative of f at x = 5 as follows. First, we compute and simplify the expression f(5 + h). f(5 + h) Then we compute and simplify the difference quotient, between x = 5 and x = 5 + h. f(5 + h) - f(5) / h The derivative of the function at x is the limit of the difference quotient as h approaches zero. f'(5) = lim h->0 (f(5 + h) - f(5)) / h