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Ch. 8 - Techniques of Integration
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 8, Problema 8.4.14

Evaluate the integrals in Exercises 1–14.
∫ (2 dx) / (x³ √(x² - 1)), where x > 1

Guida verificata passo dopo passo
1
Identify the integral to solve: \(\int \frac{2 \, dx}{x^{3} \sqrt{x^{2} - 1}}\) with the condition \(x > 1\).
Recognize that the integrand contains \(\sqrt{x^{2} - 1}\), which suggests using a trigonometric substitution such as \(x = \sec(\theta)\) because \(\sec^{2}(\theta) - 1 = \tan^{2}(\theta)\).
Perform the substitution: let \(x = \sec(\theta)\), then compute \(dx = \sec(\theta) \tan(\theta) \, d\theta\). Also, rewrite the expressions inside the integral in terms of \(\theta\).
Rewrite the integral entirely in terms of \(\theta\) by substituting \(x\), \(dx\), and \(\sqrt{x^{2} - 1}\), then simplify the resulting expression to a form that is easier to integrate.
Integrate with respect to \(\theta\), then back-substitute using \(\theta = \sec^{-1}(x)\) to express the answer in terms of \(x\).

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Integration Techniques for Rational Functions

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Trigonometric Substitution

Trigonometric substitution is used to simplify integrals containing expressions like √(x² - a²). By substituting x = a sec(θ), the radical simplifies using trigonometric identities, making the integral easier to evaluate.
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Domain Considerations and Restrictions

Understanding the domain (x > 1) is crucial because it affects the choice of substitution and the sign of expressions like √(x² - 1). It ensures the substitution is valid and the integral is evaluated correctly within the given constraints.
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