Use any method to evaluate the integrals in Exercises 15–38. Most will require trigonometric substitutions, but some can be evaluated by other methods.
∫ (1 - r²)^(5/2) / r⁸ dr

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Identify the integral to solve: \(\int \frac{(1 - r^{2})^{5/2}}{r^{8}} \, dr\).

Recognize that the integrand contains a term of the form \(\sqrt{1 - r^{2}}\) raised to a power, suggesting a trigonometric substitution related to \(r = \sin \theta\) or \(r = \cos \theta\).

Choose the substitution \(r = \sin \theta\), which implies \(dr = \cos \theta \, d\theta\). This substitution transforms \(1 - r^{2}\) into \(1 - \sin^{2} \theta = \cos^{2} \theta\).

Rewrite the integral in terms of \(\theta\) by substituting \(r = \sin \theta\), \(dr = \cos \theta \, d\theta\), and simplifying the powers of trigonometric functions accordingly.

After rewriting, simplify the integral to a form involving powers of sine and cosine functions, then use trigonometric identities or reduction formulas to integrate with respect to \(\theta\).

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주요 개념

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Trigonometric Substitution

Trigonometric substitution is a technique used to evaluate integrals involving expressions like √(a² - x²), √(a² + x²), or √(x² - a²). By substituting x with a trigonometric function, the integral simplifies into a form involving trigonometric identities, making it easier to integrate.

Integration of Rational Functions

Integration of rational functions involves integrating expressions where one polynomial is divided by another. Techniques include polynomial division, partial fraction decomposition, or substitutions to simplify the integral into manageable parts.

Power Functions and Exponent Rules

Understanding how to manipulate and integrate power functions, especially with fractional exponents, is essential. Applying exponent rules helps simplify expressions before integration, and recognizing when to use substitution or other methods is key.

Use any method to evaluate the integrals in Exercises 15–38. Most will require trigonometric substitutions, but some can be evaluated by other methods.∫ (1 - r²)^(5/2) / r⁸ dr