5: Finding Antiderivatives and Evaluating Integrals
- Page ID
- 4326
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- 5.1: Construction Accurate Graphs of Antiderivatives
- Given the graph of a function f, we can construct the graph of its antiderivative F provided that (a) we know a starting value of F, say F(a), and (b) we can evaluate the integral R b a f (x) dx exactly for relevant choices of a and b. Thus, any function with at least one antiderivative in fact has infinitely many, and the graphs of any two antiderivatives will differ only by a vertical translation.
- 5.2: The Second Fundamental Theorem of Calculus
- The Second Fundamental Theorem of Calculus is the formal, more general statement of the preceding fact: if f is a continuous function and c is any constant, then A(x) = R x c f (t) dt is the unique antiderivative of f that satisfies A(c) = 0. Together, the First and Second FTC enable us to formally see how differentiation and integration are almost inverse processes through the observations that Z x c d dt [ f (t)] dt = f (x) − f (c) and d dx "Z x c f (t) dt# = f (x).
- 5.3: Integration by Substitution
- The technique of u-substitution helps us evaluate indefinite integrals of the form f (g(x))g' (x) dx through the substitutions u = g(x) and du = g' (x) dx. A key part of choosing the expression in x to be represented by u is the identification of a function-derivative pair. To do so, we often look for an “inner” function g(x) that is part of a composite function, while investigating whether g' (x) (or a constant multiple of g' (x)) is present as a multiplying factor of the integrand.
- 5.4: Integration by Parts
- Through the method of Integration by Parts, we can evaluate indefinite integrals that involve products of basic functions through a substitution that enables us to effectively trade one of the functions in the product for its derivative, and the other for its antiderivative, in an effort to find a different product of functions that is easier to integrate.
- 5.5: Other Options for Finding Algebraic Derivatives
- The method of partial fractions enables any rational function to be antidifferentiated, because any polynomial function can be factored into a product of linear and irreducible quadratic terms. Until the development of computing algebra systems, integral tables enabled students of calculus to more easily evaluate integrals. Computer algebra systems can play an important role in finding antiderivatives, though we must be cautious to watch for unusual or unfamiliar advanced functions.
- 5.6: Numerical Integration
- Sometimes we cannot use the First Fundamental Theorem of Calculus because the integrand lacks an elementary algebraic antiderivative, we can estimate the integral’s value by using a sequence of Riemann sum approximations. The Trapezoid and Midpoint Rules are two approaches to calculate Riemann sums.
- 5.E: Finding Antiderivatives and Evaluating Integrals (Exercises)
- These are homework exercises to accompany Chapter 5 of Boelkins et al. "Active Calculus" Textmap.