/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 55 Evaluate the following definite ... [FREE SOLUTION] | 91Ó°ÊÓ

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Evaluate the following definite $$\int_{4 / \sqrt{3}}^{4} \frac{d x}{x^{2}\left(x^{2}-4\right)}$$

Short Answer

Expert verified
Question: Evaluate the definite integral $$\int_{\frac{4}{\sqrt{3}}}^{4}\frac{1}{x^2(x^2 - 4)}dx$$ using the step by step solution provided. Answer: To find the value of this definite integral, first simplify the integrand by factoring the denominator, perform the partial fraction decomposition to obtain the constants A, B, C, and D, and then integrate the simplified integrand term by term. Finally, use the Fundamental Theorem of Calculus to evaluate the integral at the given limits of integration, \(4/\sqrt{3}\) and \(4\).

Step by step solution

01

Simplify the integrand function

Notice that we can factor the denominator in the integrand. We have: $$\frac{1}{x^2(x^2 - 4)}$$ The denominator \(x^2(x^2 - 4)\) can be factored further as \(x^2( x + 2)(x - 2)\), so the function becomes: $$\frac{1}{x^2( x + 2)(x - 2)}$$ Now, perform partial fraction decomposition on the simplified function: $$\frac{1}{x^2( x + 2)(x - 2)} = \frac{A}{x} + \frac{B}{x^2} + \frac{C}{x + 2} + \frac{D}{x - 2}$$ Find the constants A, B, C, and D by solving the above equation.
02

Find the antiderivative of the simplified function

After finding A, B, C, and D, the given integrand becomes: $$\frac{1}{x^2( x + 2)(x - 2)} = \frac{A}{x} + \frac{B}{x^2} + \frac{C}{x + 2} + \frac{D}{x - 2}$$ Now, find the antiderivative of this simplified function: $$\int \frac{1}{x^2( x + 2)(x - 2)} dx = \int \left(\frac{A}{x} + \frac{B}{x^2} + \frac{C}{x + 2} + \frac{D}{x - 2}\right) dx$$ Now, find the antiderivative of each term: $$\int \frac{A}{x} dx + \int \frac{B}{x^2} dx + \int \frac{C}{x + 2} dx + \int \frac{D}{x - 2} dx$$
03

Apply the Fundamental Theorem of Calculus

Evaluate the antiderivative at the limits of integration, \(4/\sqrt{3}\) and \(4\): $$\left[ F(4) - F\left(\frac{4}{\sqrt{3}}\right) \right]$$ where \(F(x)\) is the antiderivative of the given function: $$F(x) = A \ln|x| + B \int \frac{1}{x^2} dx + C \ln|x + 2| + D \ln|x - 2|$$ Substitute the values of A, B, C, D, and the limits of integration into the equation: $$\left[ F(4) - F\left(\frac{4}{\sqrt{3}}\right) \right] = A \ln|4| - A \ln\left|\frac{4}{\sqrt{3}}\right| + B \int_{4 / \sqrt{3}}^{4} \frac{1}{x^2} dx + \left[C \ln|6| - C \ln\left|\frac{2}{\sqrt{3}}\right| - D \ln|2| + D \ln\left|\frac{2}{\sqrt{3}}\right|\right]$$ Now, simplify and calculate the definite integral. Your final answer will be the result of this evaluation.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Partial Fraction Decomposition
When dealing with complex rational expressions, partial fraction decomposition is a method used to simplify integration processes. It involves expressing a single complex fraction into a sum of simpler fractions that are easier to integrate.

In the context of the original exercise, the complex fraction \(\frac{1}{x^2(x^2 - 4)}\) is decomposed into simpler fractions. First, observe that \(x^2(x^2 - 4)\) can be factored into \(x^2(x + 2)(x - 2)\). Using this factorization, the expression can be rewritten as a combination of simpler fractions as follows: \(\frac{A}{x} + \frac{B}{x^2} + \frac{C}{x + 2} + \frac{D}{x - 2}\).

This decomposition allows us to handle each term separately during integration, making the process manageable. The constants A, B, C, and D are determined by equating coefficients from both sides, which helps in breaking down the integrand into digestible pieces.
Fundamental Theorem of Calculus
The Fundamental Theorem of Calculus connects the processes of differentiation and integration, providing a way to evaluate definite integrals.

It states that if you have a continuous function on a closed interval [a, b], and an antiderivative F of that function, then the definite integral of the function from a to b is given by \(F(b) - F(a)\). This theorem is essential because it tells us that by finding the antiderivative, we can evaluate the total accumulation of quantities described by the function over [a, b].

In the original step-by-step solution, after finding the antiderivative of each simpler fraction, you use the Fundamental Theorem to compute the definite integral. By evaluating the antiderivative at the given limits of integration \(4/\sqrt{3}\) and \(4\), you can find the net accumulation of the function over this interval.
Antiderivative
An antiderivative of a function is a function whose derivative is the original function. In simpler terms, it reverses differentiation. Finding the antiderivative is crucial for solving definite integrals, especially in applying the Fundamental Theorem of Calculus.

For the given problem, once you've broken down the integrand using partial fraction decomposition, you find the antiderivative for each fraction. Here's how it looks for the decomposed expression: \(\int \frac{A}{x} dx + \int \frac{B}{x^2} dx + \int \frac{C}{x + 2} dx + \int \frac{D}{x - 2} dx\). Each of these simpler terms has straightforward antiderivatives: \(A \ln|x| + \frac{-B}{x} + C \ln|x + 2| + D \ln|x - 2|\).

Calculating these allows you to piece together the comprehensive solution that represents the indefinite integral, which is later used to evaluate the definite integral with specific bounds.
Improper Integrals
Improper integrals arise when the interval of integration is infinite or the integrand becomes infinite within the interval. These situations demand special attention as they may not converge to a finite value.

Although the given exercise does not immediately appear to involve improper integrals, handling forms like \(\frac{1}{x^2}\), especially across unknown bounds that approach critical points (where the function is undefined), is crucial in calculus. Understanding improperly behaves parts through decomposition helps ensure that solutions converge when evaluating within limits that include infinity or undefined points.

Thus, even in non-obvious cases, preparing to handle potential divergences ensures that later evaluations provide meaningful results. These challenges are overcome using limits, and understanding the behavior of portions of the decomposed integrand near problematic points ultimately clarifies solutions.

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Most popular questions from this chapter

A differential equation of the form \(y^{\prime}(t)=F(y)\) is said to be autonomous (the function \(F\) depends only on \(y\) ). The constant function \(y=y_{0}\) is an equilibrium solution of the equation provided \(F\left(y_{0}\right)=0\) (because then \(y^{\prime}(t)=0,\) and the solution remains constant for all \(t\) ). Note that equilibrium solutions correspond to horizontal line segments in the direction field. Note also that for autonomous equations, the direction field is independent of \(t\). Consider the following equations. a. Find all equilibrium solutions. b. Sketch the direction field on either side of the equilibrium solutions for \(t \geq 0\). c. Sketch the solution curve that corresponds to the initial condition \(y(0)=1\). $$y^{\prime}(t)=y(y-3)(y+2)$$

Given a Midpoint Rule approximation \(M(n)\) and a Trapezoid Rule approximation \(T(n)\) for a continuous function on \([a, b]\) with \(n\) subintervals, show that \(T(2 n)=(T(n)+M(n)) / 2\).

For what values of \(p\) does the integral \(\int_{2}^{\infty} \frac{d x}{x \ln ^{p} x}\) exist and what is its value (in terms of \(p\) )?

Use the reduction formulas in a table of integrals to evaluate the following integrals. $$\int x^{3} e^{2 x} d x$$

The work required to launch an object from the surface of Earth to outer space is given by \(W=\int_{R}^{\infty} F(x) d x,\) where \(R=6370 \mathrm{km}\) is the approximate radius of Earth, \(F(x)=G M m / x^{2}\) is the gravitational force between Earth and the object, \(G\) is the gravitational constant, \(M\) is the mass of Earth, \(m\) is the mass of the object, and \(G M=4 \times 10^{14} \mathrm{m}^{3} / \mathrm{s}^{2}\) a. Find the work required to launch an object in terms of \(m\) b. What escape velocity \(v_{e}\) is required to give the object a kinetic energy \(\frac{1}{2} m v_{e}^{2}\) equal to \(W ?\) c. The French scientist Laplace anticipated the existence of black holes in the 18 th century with the following argument: If a body has an escape velocity that equals or exceeds the speed of light, \(c=300,000 \mathrm{km} / \mathrm{s},\) then light cannot escape the body and it cannot be seen. Show that such a body has a radius \(R \leq 2 G M / c^{2}\). For Earth to be a black hole, what would its radius need to be?

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