Math Problem Statement

Let R be the region bounded by the following curves. Find the volume of the solid generated when R is revolved about the​ x-axis. y equals StartFraction 5 Over RootIndex 4 StartRoot 1 minus x squared EndRoot EndFraction ​, y equals 0​, x equals 0​, and x equals one half

Solution

We are given the region RR bounded by the following curves:

  • y=51x24y = \frac{5}{\sqrt[4]{1 - x^2}},
  • y=0y = 0 (the x-axis),
  • x=0x = 0, and
  • x=12x = \frac{1}{2}.

We are asked to find the volume of the solid generated when this region is revolved around the x-axis. To do this, we can use the disk method.

Disk Method Formula:

The formula for the volume of a solid of revolution when revolving around the x-axis is:

V=πab[f(x)]2dxV = \pi \int_{a}^{b} \left[ f(x) \right]^2 \, dx

Here:

  • f(x)=51x24f(x) = \frac{5}{\sqrt[4]{1 - x^2}},
  • The bounds of integration are from x=0x = 0 to x=12x = \frac{1}{2}.

Thus, the volume is:

[ V = \pi \int_{0}^{\frac{1}{2}} \left[ \frac{5}{\sqrt[4]{1 - x^2}} \right]^2 , dx ]

Simplifying the integrand:

(51x24)2=251x2\left( \frac{5}{\sqrt[4]{1 - x^2}} \right)^2 = \frac{25}{\sqrt{1 - x^2}}

So the volume integral becomes:

V=π012251x2dxV = \pi \int_{0}^{\frac{1}{2}} \frac{25}{\sqrt{1 - x^2}} \, dx

Now, we will solve this integral.

Step 1: Solve the integral

This is a standard integral:

11x2dx=arcsin(x)\int \frac{1}{\sqrt{1 - x^2}} \, dx = \arcsin(x)

Therefore, the integral becomes:

V=25π01211x2dx=25π[arcsin(x)]012V = 25\pi \int_{0}^{\frac{1}{2}} \frac{1}{\sqrt{1 - x^2}} \, dx = 25\pi \left[ \arcsin(x) \right]_0^{\frac{1}{2}}

Step 2: Evaluate the integral at the bounds

V=25π[arcsin(12)arcsin(0)]V = 25\pi \left[ \arcsin\left( \frac{1}{2} \right) - \arcsin(0) \right]

We know that:

  • arcsin(12)=π6\arcsin\left( \frac{1}{2} \right) = \frac{\pi}{6},
  • arcsin(0)=0\arcsin(0) = 0.

Thus, the volume is:

V=25π(π60)=25π26V = 25\pi \left( \frac{\pi}{6} - 0 \right) = \frac{25\pi^2}{6}

Final Answer:

The volume of the solid is:

V=25π26V = \frac{25\pi^2}{6}

Would you like further details, or do you have any questions?


Here are five related questions to expand your understanding:

  1. How does the disk method differ from the shell method in finding volumes of solids of revolution?
  2. What is the geometric interpretation of the integrand in the disk method?
  3. How would the volume change if the region were revolved around the y-axis instead?
  4. Can you apply this technique to other regions bounded by different curves?
  5. What would be the result if the upper limit of integration was extended to x=1x = 1?

Tip: Always check the symmetry of the region when revolving around an axis to simplify computations!

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Math Problem Analysis

Mathematical Concepts

Calculus
Volumes of Solids of Revolution
Disk Method
Definite Integrals
Inverse Trigonometric Functions

Formulas

Volume of revolution: V = π ∫[a, b] [f(x)]^2 dx
Standard integral: ∫(1/√(1 - x^2)) dx = arcsin(x)

Theorems

Fundamental Theorem of Calculus
Disk Method for Solids of Revolution

Suitable Grade Level

Undergraduate Calculus (First Year)