26.1 APPROXIMATING SUMS: L n , R n , T n , AND M n Introduction Not only can we differentiate all the basic functions we’ve encountered, polynomials, exponential and logarithmic functions, trigonometric and inverse trigonometric functions, and rational functions, but armed with the Product and Chain Rules, we can happily differentiate any new function constructed by multiplication, division, addition, subtraction, or composition of these functions. This gives us a sense of competence and satisfaction.