/*! 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 20 In Exercises \(17-20\) , express... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

In Exercises \(17-20\) , express the integrand as a sum of partial fractions and evaluate the integrals. $$ \int \frac{x^{2} d x}{(x-1)\left(x^{2}+2 x+1\right)} $$

Short Answer

Expert verified
The integral evaluates to \(\ln|x-1| - \ln|x+1| - \frac{2}{x+1} + C\).

Step by step solution

01

Factor the Denominator

The denominator of the integrand is \((x-1)(x^2+2x+1)\). Notice that \(x^2+2x+1\) can be factored as \((x+1)^2\). So, the denominator can be rewritten as \((x-1)(x+1)^2\).
02

Set Up Partial Fractions

Express the integrand as a sum of partial fractions: \[\frac{x^{2}}{(x-1)(x+1)^2} = \frac{A}{x-1} + \frac{B}{x+1} + \frac{C}{(x+1)^2}\] where \(A\), \(B\), and \(C\) are constants to be determined.
03

Solve for Constants

Multiply through by the common denominator \((x-1)(x+1)^2\) to clear the fractions:\[x^2 = A(x+1)^2 + B(x-1)(x+1) + C(x-1)\] Expand and group like terms, matching coefficients to determine values for \(A\), \(B\), and \(C\). Solving, we find: \(A = 1\), \(B = -1\), \(C = 2\).
04

Substitute Back into Integral

Substitute the values of \(A\), \(B\), and \(C\) back into the partial fraction decomposition:\[\int \left( \frac{1}{x-1} - \frac{1}{x+1} + \frac{2}{(x+1)^2} \right) dx\]
05

Integrate Each Term Separately

Integrate each term separately:\[\int \frac{1}{x-1} \, dx - \int \frac{1}{x+1} \, dx + 2\int \frac{1}{(x+1)^2} \, dx\]Evaluating these integrals, we get:\[\ln|x-1| - \ln|x+1| - \frac{2}{x+1} + C\] where \(C\) is the constant of integration.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Integration
Understanding integration is vital for solving calculus problems involving areas, volumes, and more complex mathematical models. At its core, integration is the process of finding the integral of a function, which represents the accumulation of quantities. In the problem given, integration is applied to a rational function expressed as a sum of partial fractions. The purpose of this is to break down complex expressions into more digestible parts, each of which can be integrated separately.

When working through integrals like this one, you are essentially summing up an infinite number of infinitesimally small quantities to find a total value. This approach is the inverse operation of taking a derivative, making integration a fundamental concept in calculus. It allows you to go from a rate of change back to the original function or quantity.
Calculus
Calculus, the mathematical study of change, is founded on two main operations: differentiation and integration. In this context, calculus aids in solving integrals by offering tools and techniques, such as partial fraction decomposition, to simplify complex expressions. This optimization allows us to evaluate integrals more easily. The given exercise demonstrates this by applying calculus methods to transform a complex rational function into simpler parts that can be integrated.

Calculus is not just limited to simple integrations or derivations. It is also about understanding the why and how of the methods you use. Each step in calculus has a purpose, whether it's transforming the function, setting up equations, or evaluating integrals, every part of the process contributes to solving the mathematical problem. Mastery of calculus involves recognizing when and how to apply these different methods effectively.
Integral Evaluation
Integral evaluation involves finding the value of an integral, which is crucial for solving real-world problems involving continuous change. The given exercise required breaking down a rational function using partial fractions before evaluating each part individually. This approach simplifies the task, transforming a complex single integral into multiple simpler ones.

By using the decomposition method, each simpler integral can often be solved using standard techniques and known functions. The evaluated solution becomes the combination of these simpler solutions, which is evident in how the original problem is split and then recombined to provide the final answer as:
  • Solving \(\int \frac{1}{x-1} \, dx\) yields \(\ln|x-1|\)
  • Solving \(\int \frac{1}{x+1} \, dx\) yields \(-\ln|x+1|\)
  • Solving \(\int \frac{2}{(x+1)^2} \, dx\) results in \(-\frac{2}{x+1}\)
Becoming adept at integral evaluation allows the solving of complex mathematical models and provides clarity in diverse fields, from physics to economics.
Rational Functions
Rational functions are fractions in which both the numerator and the denominator are polynomials. They are a common type of function in mathematics that can appear in various calculus problems. In this exercise, the function \(x^2/(x-1)(x+1)^2 \) is a rational function that exhibits the complexity associated with polynomial expressions.

To simplify integration tasks involving rational functions, we use techniques like partial fraction decomposition. This involves expressing the function as a sum of simpler fractions, each of which can be tackled individually. Understanding the nature and behavior of rational functions, where asymptotes and singularities can occur, is key to anticipating potential difficulties in calculus.

By approaching such functions systematically, you gain insights into the best methods for simplification and solution. This not only aids in individual exercises but enhances overall proficiency in handling more elaborate calculus problems efficiently.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

The error function \(\quad\) The error function, $$\operatorname{erf}(x)=\frac{2}{\sqrt{\pi}} \int_{0}^{x} e^{-t^{2}} d t$$ important in probability and in the theories of heat flow and signal transmission, must be evaluated numerically because there is no elementary expression for the antiderivative of \(e^{-t^{2}}\) a. Use Simpson's Rule with \(n=10\) to estimate erf \((1)\) b. \(\operatorname{In}[0,1]\) $$\left|\frac{d^{4}}{d t^{4}}\left(e^{-t^{2}}\right)\right| \leq 12$$ Give an upper bound for the magnitude of the error of the estimate in part (a).

Pollinating flowers A biologist models the time in minutes until a bee arrives at a flowering plant with an exponential distribution having a mean of 4 minutes. If 1000 flowers are in a field, how many can be expected to be pollinated within 5 minutes?

Use a CAS to evaluate the integrals. $$\int_{0}^{2 / \pi} \sin \frac{1}{x} d x$$

Normal probability distribution The function $$f(x)=\frac{1}{\sigma \sqrt{2 \pi}} e^{-\frac{1}{2}\left(\frac{x-\mu}{w}\right)^{2}}$$ is called the normal probability density function with mean \(\mu\) and standard deviation \(\sigma .\) The number \(\mu\) tells where the distribution is centered, and \(\sigma\) measures the "scatter" around the mean. (See Section \(8.9 .\) ) \begin{equation} \begin{array}{c}{\text { From the theory of probability, it is known that }} \\\ {\int_{-\infty}^{\infty} f(x) d x=1} \\ {\text { In what follows, let } \mu=0 \text { and } \sigma=1}\end{array} \end{equation} \begin{equation} \begin{array}{l}{\text { a. Draw the graph of } f . \text { Find the intervals on which } f \text { is increas- }} \\ {\text { ing, the intervals on which } f \text { is decreasing, and any local }} \\ {\text { extreme values and where they occur. }} \\ {\text { b. Evaluate }} \\\\\quad \quad \quad \quad \quad {\int_{-n}^{n} f(x) d x}\end{array} \end{equation} \begin{equation} n=1,2, \text { and } 3 \end{equation} $$For \ n=1,2, \text { and } 3$$ \begin{equation} \begin{array}{c}{\text { c. Give a convincing argument that }} \\\ {\int_{-\infty}^{\infty} f(x) d x=1} \\ {\text { (Hint: Show that } 0 < f(x) < e^{-x / 2} \text { for } x > 1, \text { and for } b > 1} \\\ {\int_{b}^{\infty} e^{-x / 2} d x \rightarrow 0 \text { as } b \rightarrow \infty . )}\end{array} \end{equation}

Cholesterol levels The serum cholesterol levels of children aged 12 to 14 years follows a normal distribution with mean \(\mu=162\) mg/dl and standard deviation \(\sigma=28\) mg/dl. In a population of 1000 of these children, how many would you expect to have serum cholesterol levels between 165 and 193\(?\) between 148 and 167\(?\)

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.