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Ch. 8 - Integration Techniques
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 8, Problem 8.1.65d

 Explain why or why not Determine whether the following statements are true and give an explanation or counterexample.
d. ∫(1/eˣ) dx = ln eˣ + C.

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Step 1: Analyze the given integral ∫(1/eˣ) dx. The integrand is 1/eˣ, which can be rewritten as e⁻ˣ using the property of exponents.
Step 2: Recall the standard rule for integrating exponential functions. The integral of e⁻ˣ with respect to x is ∫e⁻ˣ dx = -e⁻ˣ + C, where C is the constant of integration.
Step 3: Compare the given statement ∫(1/eˣ) dx = ln eˣ + C with the correct integral result. Note that ln eˣ simplifies to x because the natural logarithm and exponential functions are inverses of each other.
Step 4: Observe that the given statement suggests the integral of 1/eˣ is ln eˣ + C, which simplifies to x + C. This is incorrect because the integral of 1/eˣ is actually -e⁻ˣ + C, not x + C.
Step 5: Conclude that the statement ∫(1/eˣ) dx = ln eˣ + C is false. Provide the correct result, ∫(1/eˣ) dx = -e⁻ˣ + C, as a counterexample to demonstrate why the given statement is incorrect.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Integration

Integration is a fundamental concept in calculus that involves finding the antiderivative of a function. It is the process of determining the area under a curve represented by a function over a specified interval. Understanding integration is crucial for evaluating definite and indefinite integrals, which are essential for solving problems related to areas, volumes, and other applications in mathematics and physics.
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Natural Logarithm

The natural logarithm, denoted as ln, is the logarithm to the base e, where e is approximately 2.71828. It is an important function in calculus, particularly in integration and differentiation. The natural logarithm has unique properties, such as ln(e^x) = x, which are useful for simplifying expressions and solving equations involving exponential functions.
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Derivative of the Natural Logarithmic Function

Exponential Functions

Exponential functions are mathematical functions of the form f(x) = a * e^(bx), where a and b are constants, and e is the base of the natural logarithm. These functions are characterized by their rapid growth or decay and are widely used in various fields, including finance, biology, and physics. Understanding the properties of exponential functions is essential for evaluating integrals involving e^x and applying the rules of integration correctly.
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Related Practice
Textbook Question

The Eiffel Tower Property Let R be the region between the curves y = e^(-c·x) and y = -e^(-c·x) on the interval [a, ∞), where a ≥ 0 and c > 0.

The center of mass of R is located at (x̄, 0), where x̄ = [∫(a to ∞) x·e^(-c·x) dx] / [∫(a to ∞) e^(-c·x) dx]

(The profile of the Eiffel Tower is modeled by these two exponential curves; see the Guided Project "The exponential Eiffel Tower")

d. Prove this property holds for any a ≥ 0 and c > 0:

The tangent lines to y = ±e^(-c·x) at x = a always intersect at R's center of mass

(Source: P. Weidman and I. Pinelis, Comptes Rendu, Mechanique, 332, 571-584, 2004)

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Textbook Question

66–71. {Use of Tech} Estimating error Refer to Theorem 8.1 in the following exercises.

69. Let f(x) = sin(eˣ).

d. Find an upper bound on the absolute error in the estimate found in part (a) using Theorem 8.1.

Textbook Question

66–71. {Use of Tech} Estimating error Refer to Theorem 8.1 in the following exercises.

66. Let f(x) = cos(x²).

d. Use Theorem 8.1 to find an upper bound on the absolute error in the estimate found in part (a).

Textbook Question

Explain why or why not Determine whether the following statements are true and give an explanation or counterexample.

d. Using the substitution u = tan(x) in ∫ (tan²x / (tan x - 1)) dx leads to ∫ (u² / (u - 1)) du.

Textbook Question

101. Many methods needed Show that the integral from ∫(from 0 to ∞)(sqrt(x) * ln x) / (1 + x)^2 dx equals pi, following these steps

d. Evaluate the remaining integral using the change of variables z = sqrt(x)

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Textbook Question

2. Give an example of each of the following.

d. A repeated irreducible quadratic factor