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Ch. 8 - Integration Techniques
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243당신이 사용하는 게 아니라요?교과서 변경
8장, 문제 8.RE.48

2–74. Integration techniques Use the methods introduced in Sections 8.1 through 8.5 to evaluate the following integrals.
48. ∫ sin(3x) cos⁶(3x) dx

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Step 1: Recognize that the integral involves a product of trigonometric functions, specifically sin(3x) and cos⁶(3x). To simplify, consider using a substitution method. Let u = cos(3x), which implies that du = -3sin(3x) dx.
Step 2: Rewrite the integral in terms of u. Substitute sin(3x) dx with -du/3 and cos⁶(3x) with u⁶. The integral becomes: ∫ sin(3x) cos⁶(3x) dx = -1/3 ∫ u⁶ du.
Step 3: Apply the power rule for integration to evaluate ∫ u⁶ du. Recall that the power rule states: ∫ uⁿ du = uⁿ⁺¹ / (n+1) + C, where n ≠ -1.
Step 4: Substitute back u = cos(3x) into the result obtained from the integration step to express the solution in terms of x.
Step 5: Add the constant of integration (C) to complete the solution, as this is an indefinite integral.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Integration Techniques

Integration techniques are methods used to find the integral of a function. Common techniques include substitution, integration by parts, and trigonometric identities. Understanding these methods is essential for evaluating complex integrals, as they allow for simplification and manipulation of the integrand to facilitate integration.
추천 영상:
06:18
Integration by Parts for Definite Integrals

Trigonometric Identities

Trigonometric identities are equations that relate the angles and sides of triangles, and they are crucial in simplifying integrals involving trigonometric functions. For example, the product-to-sum identities can transform products of sine and cosine into sums, making integration more manageable. Familiarity with these identities is vital for solving integrals like ∫ sin(3x) cos⁶(3x) dx.
추천 영상:
7:17
Verifying Trig Equations as Identities

Substitution Method

The substitution method is a technique used in integration where a new variable is introduced to simplify the integral. By substituting a part of the integrand with a single variable, the integral can often be transformed into a more straightforward form. This method is particularly useful when dealing with composite functions or when the integrand contains a function and its derivative.
추천 영상:
07:33
Euler's Method