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Ch. 3 - Derivatives
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243당신이 사용하는 게 아니라요?교과서 변경
3장, 문제 3.5.57

Find y'' for the following functions.
y = x sin x

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First, identify that the function y = x sin(x) is a product of two functions: u(x) = x and v(x) = sin(x). To find the first derivative y', use the product rule: (uv)' = u'v + uv'.
Calculate the derivative of u(x) = x, which is u'(x) = 1.
Calculate the derivative of v(x) = sin(x), which is v'(x) = cos(x).
Apply the product rule: y' = u'v + uv' = (1)(sin(x)) + (x)(cos(x)) = sin(x) + x cos(x).
To find the second derivative y'', differentiate y' = sin(x) + x cos(x) with respect to x. Use the sum rule and the product rule again for the term x cos(x). The derivative of sin(x) is cos(x), and for x cos(x), apply the product rule: (x cos(x))' = (1)(cos(x)) + (x)(-sin(x)) = cos(x) - x sin(x). Therefore, y'' = cos(x) + (cos(x) - x sin(x)).

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주요 개념

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

Differentiation

Differentiation is the process of finding the derivative of a function, which represents the rate of change of the function with respect to its variable. In this context, we need to differentiate the function y = x sin x to find its first derivative, y', and then differentiate y' to find the second derivative, y''. This process is fundamental in calculus for analyzing the behavior of functions.
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가이드 코스
05:53
Finding Differentials

Product Rule

The Product Rule is a formula used to differentiate products of two functions. It states that if you have two functions u(x) and v(x), the derivative of their product is given by u'v + uv'. In the case of y = x sin x, we will apply the Product Rule to differentiate the function correctly, ensuring we account for both components of the product.
추천 영상:
05:18
The Product Rule

Second Derivative

The second derivative of a function, denoted as y'', is the derivative of the first derivative, y'. It provides information about the curvature of the function and can indicate points of inflection. In this problem, finding y'' will help us understand how the rate of change of y = x sin x evolves, which is crucial for analyzing its behavior in applications such as motion or optimization.
추천 영상:
06:02
The Second Derivative Test: Finding Local Extrema