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5: Investigating Integrals

  • Page ID
    116604
    • Gilbert Strang & Edwin “Jed” Herman
    • OpenStax

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    • 5.1: Antiderivatives and Indefinite Integrals
      This section introduces antiderivatives and indefinite integrals, explaining the process of reversing differentiation to find the original function. It covers basic integration rules, notation, and the concept of the constant of integration. Examples demonstrate finding antiderivatives for various functions, establishing foundational skills for solving integral problems.
    • 5.2: Approximating Areas
      This section introduces methods for approximating the area under a curve, such as the Left and Right Riemann Sums. It explains how these methods estimate area by dividing the region into shapes with easily computed areas, which improve accuracy as the number of subdivisions increases. Examples illustrate applying each technique to approximate integrals.
    • 5.3: The Definite Integral
      If f(x) is a function defined on an interval [a,b], the definite integral of f from a to b is given by \[∫^b_af(x)dx=\lim_{n→∞} \sum_{i=1}^nf(x^∗_i)Δx,\] provided the limit exists. If this limit exists, the function f(x) is said to be integrable on [a,b], or is an integrable function. The numbers a and b are called the limits of integration; specifically, a is the lower limit and b is the upper limit. The function f(x) is the integrand, and x is the variable of integration.
    • 5.4: The Fundamental Theorem of Calculus
      The Fundamental Theorem of Calculus gave us a method to evaluate integrals without using Riemann sums. The drawback of this method, though, is that we must be able to find an antiderivative, and this is not always easy.
    • 5.5: The Net Change Theorem, Distances, and Symmetry
      The net change theorem states that when a quantity changes, the final value equals the initial value plus the integral of the rate of change. Net change can be a positive number, a negative number, or zero. The area under an even function over a symmetric interval can be calculated by doubling the area over the positive x-axis. For an odd function, the integral over a symmetric interval equals zero, because half the area is negative.
    • 5.6: Integration by Substitution
      In this section we examine a technique, called integration by substitution, to help us find antiderivatives. Specifically, this method helps us find antiderivatives when the integrand is the result of a chain-rule derivative.
    • 5.7: Chapter 5 Review Exercises


    This page titled 5: Investigating Integrals is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Gilbert Strang & Edwin “Jed” Herman (OpenStax) via source content that was edited to the style and standards of the LibreTexts platform.