/*! 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 23 Evaluate the integral. $$\int ... [FREE SOLUTION] | 91Ó°ÊÓ

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Evaluate the integral. $$\int \sec ^{2}(2 x-1) d x$$

Short Answer

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

Step by step solution

01

Recognize the Integral Form

The integral we need to solve is \( \int \sec^2(2x - 1) \, dx \). This is similar to the integral \( \int \sec^2(u) \, du = \tan(u) + C \), where \( C \) is the constant of integration. So, we need to rewrite our integral in this form.
02

Identify Substitution

Let \( u = 2x - 1 \). This substitution simplifies the expression inside the integral. Consequently, we need to find \( du \) in terms of \( dx \).
03

Compute Differential

Differentiate \( u = 2x - 1 \) with respect to \( x \), giving \( \frac{du}{dx} = 2 \). This implies that \( du = 2 \, dx \), or rearranged, \( dx = \frac{1}{2} \, du \).
04

Substitute and Transform Integral

Substitute \( u = 2x - 1 \) and \( dx = \frac{1}{2} \, du \) into the integral. The new integral becomes \( \int \sec^2(u) \cdot \frac{1}{2} \, du = \frac{1}{2} \int \sec^2(u) \, du \).
05

Solve the Transformed Integral

The integral \( \frac{1}{2} \int \sec^2(u) \, du \) is \( \frac{1}{2} \tan(u) + C \). Here, \( C \) is the constant of integration.
06

Substitute Back to Original Variable

Substitute \( u = 2x - 1 \) back into the solution, resulting in \( \frac{1}{2} \tan(2x - 1) + C \).

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Key Concepts

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

Integration Techniques
Integration techniques are crucial for solving various integral calculus problems. When evaluating integrals, it's important to identify the technique that best simplifies and solves the integral. Some common techniques include:
  • Basic antiderivatives
  • Substitution method
  • Integration by parts
  • Partial fraction decomposition
  • Trigonometric identities and substitutions
In our original exercise, we used substitution to evaluate the integral. Recognizing the form of the integral helps us decide on an approach. In this case, matching the problem to a known integral form helped clarify that substitution was a useful technique. Identifying patterns within integrals is a skill that, with practice, greatly simplifies the process of finding solutions.
Trigonometric Integrals
Trigonometric integrals involve integrals of trigonometric functions, such as sine, cosine, or secant squared, among others. These integrals frequently occur in various areas of calculus and engineering. Working with trigonometric integrals requires familiarity with trigonometric identities and patterns.In the provided problem, we had an integral of the form \( \int \sec^2(u) \, du \), which is a standard trigonometric integral. This integral is known to simplify to \( \tan(u) + C \), the antiderivative of \( \sec^2(u) \). Identifying the trigonometric function's integral form allows for straightforward substitution and integration, as trigonometric identities help reduce complex expressions to manageable forms. Practicing these integrals reinforces understanding of both trigonometric and calculus fundamentals.
Substitution Method
The substitution method is a powerful technique in integration for changing the variable of integration. By replacing a variable, you can transform a complex integral into a simpler one, which is easier to evaluate. The basic steps of this method include:
  • Choosing a substitution \( u = g(x) \) that simplifies the integral
  • Finding the differential \( du \) as \( g'(x) \, dx \)
  • Rewriting the integral in terms of \( u \) and \( du \)
  • Evaluating the simpler integral
  • Substituting back the original variable
In our exercise, we chose \( u = 2x - 1 \), simplifying the expression within the integral. Differentiate \( u \) to find \( du = 2 \, dx \), or \( dx = \frac{1}{2} \, du \). Substitute these into the original integral to transform it into a simpler form: \( \int \sec^2(u) \cdot \frac{1}{2} \, du \). Completing the integration and substituting back \( u = 2x - 1 \) provided the final solution. Mastering substitution requires practice, but it is an essential tool for solving a range of integrals efficiently.

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Most popular questions from this chapter

Does there exist a quadratic polynomial \(a x^{2}+b x+c\) such that the integration $$ \int \frac{x}{a x^{2}+b x+c} d x $$ produces a function with no logarithmic terms? If so, give an example; if not, explain why no such polynomial can exist.

Later in the text, we will show that $$ \int_{0}^{+\infty} e^{-x^{2}} d x=\frac{1}{2} \sqrt{\pi} $$ Confirm that this is reasonable by using a CAS or a calculator with a numerical integration capability.

Integrate by hand and check your answers using a CAS. $$ \int \frac{d x}{16 x^{3}-4 x^{2}+4 x-1} $$

Express the improper integral as a limit, and then evaluate that limit with a CAS. Confirm the answer by evaluating the integral directly with the CAS. $$ \int_{0}^{+\infty} e^{-x} \cos x d x $$

A transform is a formula that converts or "transforms" one function into another. Transforms are used in applications to convert a difficult problem into an easier problem whose solution can then be used to solve the original difficult problem. The Laplace transform of a function \(f(t),\) which plays an important role in the study of differential equations, is denoted by \(\mathscr{L}\\{f(t)\\}\) and is defined by $$ \mathscr{L}\\{f(t)\\}=\int_{0}^{+\infty} e^{-s t} f(t) d t $$ In this formula \(s\) is treated as a constant in the integration process; thus, the Laplace transform has the effect of transforming \(f(t)\) into a function of \(s .\) Use this formula in these exercises. In each part, find the Laplace transform. $$\begin{array}{llll}{\text { (a) } f(t)=t,} & {s>0} & {\text { (b) } f(t)=t^{2}, s>0}\end{array}$$

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