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Ch. 6 - Applications of Integration
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 6, Problem 6.R.27

27–33. Multiple regions The regions R₁,R₂, and R₃ (see figure) are formed by the graphs of y = 2√x,y = 3−x,and x=3.
Find the area of each of the regions R₁,R₂, and R₃.
Graph showing regions R₁, R₂, and R₃ formed by curves and lines, with labels indicating their areas.

Verified step by step guidance
1
Identify the curves and lines that bound each region R₁, R₂, and R₃. From the graph, R₁ is bounded by y = 3 - x and y = 2\(\sqrt{x}\), R₂ is bounded by y = 2\(\sqrt{x}\) and y = 3 - x, and R₃ is bounded by y = 2\(\sqrt{x}\) and the vertical line x = 3.
Find the points of intersection between the curves to determine the limits of integration. Solve for x where y = 2\(\sqrt{x}\) equals y = 3 - x by setting 2\(\sqrt{x}\) = 3 - x and solving for x.
For region R₁, set up the integral for the area between y = 3 - x (upper curve) and y = 2\(\sqrt{x}\) (lower curve) from x = 0 to the intersection point found in step 2. The area is given by \(\int_0^{x_1} [(3 - x) - 2\sqrt{x}] \, dx\).
For region R₂, set up the integral for the area between y = 2\(\sqrt{x}\) (upper curve) and y = 3 - x (lower curve) from the intersection point found in step 2 to x = 3. The area is given by \(\int_{x_1}^3 [2\sqrt{x} - (3 - x)] \, dx\).
For region R₃, observe that it is bounded by y = 2\(\sqrt{x}\) and the vertical line x = 3, and the x-axis (y=0). Set up the integral for the area under y = 2\(\sqrt{x}\) from x = 3 to the upper boundary (which is the line x=3, so the vertical boundary). Since the region is a vertical slice, the area is \(\int_3^{x_2} 2\sqrt{x} \, dx\), where x_2 is the upper limit determined by the graph (likely x=3). Confirm the exact limits from the graph and set up the integral accordingly.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Finding Points of Intersection

To determine the boundaries of the regions, it is essential to find the points where the curves intersect. This involves solving equations like 2√x = 3 - x to find x-values where the graphs meet, which define the limits of integration for calculating areas.
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Definite Integrals for Area Calculation

The area between curves is found by integrating the difference of the functions over the interval defined by their points of intersection. For example, the area between y = 3 - x and y = 2√x from one intersection point to another is given by the integral of their difference.
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Definition of the Definite Integral

Partitioning the Plane into Regions

The problem involves multiple regions formed by the intersection of curves and lines. Understanding how to partition the plane into distinct regions (R₁, R₂, R₃) and setting up separate integrals for each is crucial for correctly computing their individual areas.
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Area of Polar Regions
Related Practice
Textbook Question

14–25. {Use of Tech} Areas of regions Determine the area of the given region.


The region in the first quadrant bounded by y = x/6 and y = 1−|x/2−1|

Textbook Question

Area and volume The region R is bounded by the curves x = y²+2,y=x−4, and y=0 (see figure).

b. Write a single integral that gives the volume of the solid generated when R is revolved about the x-axis.

Textbook Question

43–55. Volumes of solids Choose the general slicing method, the disk/washer method, or the shell method to answer the following questions.


The region bounded by the graphs of y = 2x,y = 6−x, and y = 0 is revolved about the line y = −2 and the line x = −2. Find the volumes of the resulting solids. Which one is greater?

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Textbook Question

Comparing volumes Let R be the region bounded by y=1/x^p and the x-axis on the interval [1, a], where p>0 and a>1 (see figure). Let Vₓ and Vᵧ be the volumes of the solids generated when R is revolved about the x- and y-axes, respectively.


c. Find a general expression for Vₓ in terms of a and p. Note that p=1/2 is a special case. What is Vₓ when p=1/2?

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Textbook Question

Two methods The region R in the first quadrant bounded by the parabola y = 4-x² and coordinate axes is revolved about the y-axis to produce a dome-shaped solid. Find the volume of the solid in the following ways:


a. Apply the disk method and integrate with respect to y.

Textbook Question

35-38. Area and volume Let R be the region in the first quadrant bounded by the graph of

Find the area of the region R.