Chapter 8: Problem 25
Use the table of integrals at the back of the book to evaluate the integrals. \(\int \frac{d s}{\left(9-s^{2}\right)^{2}}\)
Short Answer
Expert verified
\(\int \frac{ds}{(9-s^2)^2} = \frac{s}{18(9-s^2)} + \frac{1}{54}\arcsin\left(\frac{s}{3}\right) + C\).
Step by step solution
01
Recognize the Form of the Integral
The integral we have is \(\int \frac{ds}{(9-s^{2})^{2}}\). This resembles a standard form usually found in a table of integrals: \(\int \frac{dx}{(a^2-x^2)^2}\) or a similar format. Our goal is to match this with the appropriate table entry.
02
Identify Constants in Integral
In our integral, \(a\) is a constant, and we compare \(9\) and \(s^2\) with the general form. Here, we recognize that \(9 = 3^2\), so \(a = 3\). Our integral now matches the form \(\int \frac{ds}{(3^2-s^{2})^{2}}\).
03
Find Matching Integral from Table
Referring to the table of integrals, we look for an entry that matches our form \(\int \frac{ds}{(a^2-s^2)^{2}}\). The table entry might suggest using a specific substitution or provide a direct formula.
04
Apply the Formula from the Table
Assuming the table provides: \(\int \frac{dx}{(a^2-x^2)^2} = \frac{x}{2a^2(a^2-x^2)} + \frac{1}{2a^3}\arcsin\left(\frac{x}{a}\right) + C\). We apply this to our integral with \(a = 3\), so our result becomes: \(\frac{s}{2(3^2)(9-s^2)} + \frac{1}{2(3)^3}\arcsin\left(\frac{s}{3}\right) + C\).
05
Simplify the Expression
Simplify the expression: \(\frac{s}{18(9-s^2)} + \frac{1}{54}\arcsin\left(\frac{s}{3}\right) + C\). This is often the final solution as provided in the table.
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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 methods used to find the integral of a function, which is a fundamental tool in calculus. The primary goal is to determine the antiderivative or the area under a curve.
Several techniques exist to tackle various integrals, including:
Several techniques exist to tackle various integrals, including:
- Substitution: This involves replacing a part of the integral with a single variable to make the integration manageable. It's often used when the integral contains a function and its derivative.
- Integration by Parts: This is useful for products of functions, relying on the rule: \( \int u \, dv = uv - \int v \, du \. \).
- Partial Fraction Decomposition: Useful for rational functions, this technique splits a complex fraction into simpler parts.
Table of Integrals
A table of integrals is a collection of formulas for integrals of common function types. These tables come in handy to quickly solve integrals that match known patterns.
To utilize a table, follow these steps:
To utilize a table, follow these steps:
- Identify the Form: Compare your integral with those in the table. Look for similar structures, terms, and forms.
- Match the Constants: Check if constants in the integral can be identified with those in a form from the table. Adjust your integral to fit this form if possible.
- Apply the Formula: Once a match is found, directly apply the corresponding formula from the table to solve the integral.
Trigonometric Substitution
Trigonometric substitution is a technique used in integration to handle integrals involving quadratic expressions, especially those of the form \( a^2 - x^2 \), \( a^2 + x^2 \), and \( x^2 - a^2 \).
The idea is to substitute a trigonometric function for the variable to simplify the integral. For example:
The idea is to substitute a trigonometric function for the variable to simplify the integral. For example:
- For \( \sqrt{a^2 - x^2} \), use \( x = a \sin(\theta) \).
- For \( \sqrt{a^2 + x^2} \), use \( x = a \tan(\theta) \).
- For \( \sqrt{x^2 - a^2} \), use \( x = a \sec(\theta) \).