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Ch. 6 - Applications of Integration
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243당신이 사용하는 게 아니라요?교과서 변경
6장, 문제 6.3.64

Let f(x) = {x   if 0≤x≤2
      2x−2  if 2<x≤5
      −2x+18 if 5<x≤6. 


Find the volume of the solid formed when the region bounded by the graph of f, the x-axis, and the line x=6 is revolved about the x-axis.
fig

검증된 단계별 안내
1
Identify the piecewise function \( f(x) \) defined as: \[ f(x) = \begin{cases} x & \text{if } 0 \leq x \leq 2 \\ 2x - 2 & \text{if } 2 < x \leq 5 \\ -2x + 18 & \text{if } 5 < x \leq 6 \end{cases} \] This function describes the height of the region above the x-axis for each interval.
Recall that the volume of the solid formed by revolving the region bounded by \( f(x) \), the x-axis, and the vertical line \( x = 6 \) about the x-axis can be found using the disk method. The volume \( V \) is given by the integral: \[ V = \pi \int_a^b [f(x)]^2 \, dx \] where \( a = 0 \) and \( b = 6 \) in this problem.
Since \( f(x) \) is piecewise, split the integral into three parts corresponding to the intervals: \[ V = \pi \left( \int_0^2 (x)^2 \, dx + \int_2^5 (2x - 2)^2 \, dx + \int_5^6 (-2x + 18)^2 \, dx \right) \]
Set up each integral explicitly: - For \( 0 \leq x \leq 2 \): \[ \int_0^2 x^2 \, dx \] - For \( 2 < x \leq 5 \): \[ \int_2^5 (2x - 2)^2 \, dx \] - For \( 5 < x \leq 6 \): \[ \int_5^6 (-2x + 18)^2 \, dx \]
Evaluate each integral separately and then sum the results. Finally, multiply the sum by \( \pi \) to find the total volume of the solid formed by revolving the region about the x-axis.

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주요 개념

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

Piecewise Functions

A piecewise function is defined by different expressions over distinct intervals of the domain. Understanding how to interpret and work with each piece separately is essential, especially when integrating or analyzing the function over its entire domain.
추천 영상:
가이드 코스
05:36
Piecewise Functions

Volume of Solids of Revolution

The volume of a solid formed by revolving a region around an axis can be found using methods like the disk or washer method. This involves integrating the cross-sectional area, typically π[f(x)]², along the axis of revolution.
추천 영상:
04:48
Finding Volume Using Disks

Definite Integration

Definite integration calculates the accumulation of quantities, such as area or volume, over an interval. For solids of revolution, it is used to sum the volumes of infinitesimally thin disks or washers across the given bounds.
추천 영상:
가이드 코스
05:43
Definition of the Definite Integral