Area: Find the area between the x-axis and the curve y = √(1 + cos 4x), for 0 ≤ x ≤ π.
Ch. 8 - Techniques of Integration
8장, 문제 8.5.38
In Exercises 33–38, perform long division on the integrand, write the proper fraction as a sum of partial fractions, and then evaluate the integral.
∫ 2y⁴ / (y³ - y² + y - 1) dy
검증된 단계별 안내1
First, perform polynomial long division of the integrand \( \frac{2y^{4}}{y^{3} - y^{2} + y - 1} \). Since the degree of the numerator (4) is higher than the degree of the denominator (3), divide \( 2y^{4} \) by \( y^{3} \) to find the first term of the quotient.
Multiply the entire denominator \( y^{3} - y^{2} + y - 1 \) by the term found in the previous step and subtract this product from the numerator \( 2y^{4} \) to find the remainder polynomial. This remainder will have degree less than 3.
Rewrite the original integrand as the sum of the quotient polynomial plus the remainder over the original denominator: \[ \frac{2y^{4}}{y^{3} - y^{2} + y - 1} = \text{quotient} + \frac{\text{remainder}}{y^{3} - y^{2} + y - 1} \].
Next, factor the denominator \( y^{3} - y^{2} + y - 1 \) if possible, to express the proper fraction \( \frac{\text{remainder}}{y^{3} - y^{2} + y - 1} \) as a sum of partial fractions. Look for linear or quadratic factors.
Set up the partial fraction decomposition with unknown coefficients corresponding to each factor of the denominator. Then, multiply both sides by the denominator and equate coefficients of like powers of \( y \) to solve for these unknowns. Finally, integrate each term separately.

비슷한 문제에 대한 검증된 영상 답변:
이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
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주요 개념
질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.
Polynomial Long Division
Polynomial long division is a method used to divide a polynomial by another polynomial of lower degree. It helps simplify the integrand by separating it into a polynomial plus a proper fraction, making the integral easier to handle. This step is essential when the degree of the numerator is equal to or greater than the denominator.
추천 영상:
Taylor Polynomials
Partial Fraction Decomposition
Partial fraction decomposition breaks down a proper rational function into a sum of simpler fractions with linear or quadratic denominators. This technique simplifies integration by allowing each term to be integrated individually. It requires factoring the denominator and expressing the fraction as a sum of unknown coefficients to solve.
추천 영상:
가이드 코스
Partial Fraction Decomposition: Distinct Linear Factors
Integration of Rational Functions
Integrating rational functions often involves rewriting the integrand using long division and partial fractions. After decomposition, standard integral formulas for logarithmic and inverse trigonometric functions can be applied. Understanding these integration techniques is crucial for evaluating complex rational integrals.
추천 영상:
Intro to Rational Functions
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