Math Problem Statement
Find the volume V of the solid obtained by rotating the region bounded by the given curves about the specified line.
y =
x − 1
, y = 0, x = 8; about the x-axis
Solution
To find the volume of the solid obtained by rotating the region bounded by the curves about the -axis, we can apply the Disk Method.
Step-by-Step Approach:
-
Identify the curves and region:
- The region is bounded by:
- (the x-axis)
- The region is bounded by:
-
Set up the Disk Method formula:
The volume of a solid obtained by rotating a region about the -axis is given by: where is the function describing the curve being rotated, and are the limits of integration along the -axis.
-
Set up the integral:
The curve will be rotated about the -axis. This gives the radius of each disk as . The limits of integration are from (where ) to (as given in the problem).
So, the integral becomes:
-
Expand the integrand:
First, expand : Now, the integral becomes:
-
Integrate:
Now, integrate each term:
-
Evaluate the definite integral:
First, evaluate at :
Next, evaluate at :
Now, subtract the two values:
-
Final answer:
The volume of the solid is:
Do you need further details or clarifications?
Here are 5 related questions to expand on the topic:
- How does the Disk Method differ from the Shell Method?
- What would the volume be if the region were rotated about the line ?
- Can you solve the same problem using cylindrical shells instead of disks?
- How would the volume change if the curve were rotated about the -axis?
- How do you find the volume of a solid with a more complex boundary, such as ?
Tip: Always check the limits of integration carefully when setting up an integral for volumes of rotation.
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Math Problem Analysis
Mathematical Concepts
Integral Calculus
Volumes of Solids of Revolution
Disk Method
Formulas
Volume of solid of revolution: V = π ∫[a to b] [f(x)]^2 dx
f(x) = x - 1
Theorems
Disk Method
Suitable Grade Level
Grades 11-12
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