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Ch. 7 - Logarithmic, Exponential Functions, and Hyperbolic Functions
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 7, Problem 7.RE.9

2–9. Integrals Evaluate the following integrals.


∫₀¹ (x² / (9 − x⁶)) dx

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1
Identify the integral to be evaluated: \(\int_0^1 \frac{x^2}{9 - x^6} \, dx\).
Look for a substitution that simplifies the denominator. Notice that the denominator is \(9 - x^6\), and the numerator is \(x^2\). Consider substituting \(u = x^3\) because \(x^6 = (x^3)^2 = u^2\).
Compute the differential \(du\): since \(u = x^3\), then \(du = 3x^2 \, dx\), which implies \(x^2 \, dx = \frac{du}{3}\).
Rewrite the integral in terms of \(u\): change the limits accordingly. When \(x=0\), \(u=0^3=0\); when \(x=1\), \(u=1^3=1\). The integral becomes \(\int_0^1 \frac{1}{9 - u^2} \cdot \frac{du}{3}\).
Simplify the integral to \(\frac{1}{3} \int_0^1 \frac{1}{9 - u^2} \, du\). This is a standard integral that can be solved using partial fractions or recognizing it as a form related to inverse hyperbolic functions or logarithms.

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Key Concepts

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

Definite Integrals

A definite integral calculates the net area under a curve between two specific limits. It is represented as ∫_a^b f(x) dx, where a and b are the lower and upper bounds. Evaluating definite integrals often involves finding an antiderivative and then applying the Fundamental Theorem of Calculus.
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Substitution Method

The substitution method simplifies integrals by changing variables to transform the integral into a more manageable form. It involves choosing a substitution u = g(x) such that the integral in terms of u is easier to evaluate. This technique is especially useful when the integrand contains composite functions.
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Euler's Method

Handling Rational Functions with Polynomial Denominators

Integrals involving rational functions with polynomial denominators often require algebraic manipulation or substitution to simplify. Recognizing patterns, such as powers in numerator and denominator, helps in choosing an appropriate substitution or partial fraction decomposition to evaluate the integral.
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Limits of Rational Functions: Denominator = 0
Related Practice
Textbook Question

2–9. Integrals Evaluate the following integrals.


∫₁⁴ (10^{√x} / √x) dx

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Textbook Question

Moore’s Law In 1965, Gordon Moore observed that the number of transistors that could be placed on an integrated circuit was approximately doubling each year, and he predicted that this trend would continue for another decade. In 1975, Moore revised the doubling time to every two years, and this prediction became known as Moore’s Law.


a. In 1979, Intel introduced the Intel 8088 processor; each of its integrated circuits contained 29,000 transistors. Use Moore’s revised doubling time to find a function y(t) that approximates the number of transistors on an integrated circuit t years after 1979.

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Textbook Question

2–9. Integrals Evaluate the following integrals.


∫ dx / √(x² − 9),x > 3

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Textbook Question

Caffeine An adult consumes an espresso containing 75 mg of caffeine. If the caffeine has a half-life of 5.5 hours, when will the amount of caffeine in her bloodstream equal 30 mg?

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Textbook Question

Population growth The population of a large city grows exponentially with a current population of 1.3 million and a predicted population of 1.45 million 10 years from now.


b. Find the doubling time of the population.

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Textbook Question

Savings account A savings account advertises an annual percentage yield (APY) of 5.4%, which means that the balance in the account increases at an annual growth rate of 5.4%/yr.


b. What is the doubling time of the balance?

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