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Use the disk method or the shell method to find the volume of the solid generated by revolving the region bounded by the graphs of the equations about each given line. \[ \begin{array}{r}y=x^{3} \\ y=0 \\ x=2\end{array} \] (a) \( x \)-axis (b) \( y \)-axis (c) \( x=4 \) (b)

Ask by Mathis Harmon. in the United States
Feb 25,2025

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To find the volume of the solid generated by revolving the region bounded by \( y = x^3 \), \( y = 0 \), and \( x = 2 \) about each given line, use the disk method for the \( x \)-axis and the shell method for the \( y \)-axis and \( x = 4 \). - **(a) \( x \)-axis**: Volume = \( \frac{128\pi}{7} \) cubic units. - **(b) \( y \)-axis**: Volume = \( \frac{64\pi}{5} \) cubic units. - **(c) \( x = 4 \)**: Volume = \( \frac{96\pi}{5} \) cubic units.

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To find the volume of the solid generated by revolving the region bounded by the graphs of the equations about each given line, we can use the disk method or the shell method. Given equations: \[ y = x^3 \] \[ y = 0 \] \[ x = 2 \] (a) Revolving about the \( x \)-axis: The volume of the solid generated by revolving the region about the \( x \)-axis can be found using the disk method. The formula for the volume of a solid of revolution about the \( x \)-axis is: \[ V = \pi \int_{a}^{b} [f(x)]^2 dx \] In this case, the function is \( f(x) = x^3 \), and the limits of integration are from \( x = 0 \) to \( x = 2 \). Let's calculate the volume using the disk method. Evaluate the integral by following steps: - step0: Evaluate using formulas and rules: \(\pi \times \int_{0}^{2} \left(x^{3}\right)^{2} dx\) - step1: Multiply the exponents: \(\pi \times \int_{0}^{2} x^{3\times 2} dx\) - step2: Multiply the numbers: \(\pi \times \int_{0}^{2} x^{6} dx\) - step3: Evaluate the integral: \(\pi \times \frac{128}{7}\) - step4: Multiply: \(\frac{\pi \times 128}{7}\) - step5: Multiply: \(\frac{128\pi }{7}\) The volume of the solid generated by revolving the region about the \( x \)-axis is \( \frac{128\pi}{7} \) cubic units. (b) Revolving about the \( y \)-axis: To find the volume of the solid generated by revolving the region about the \( y \)-axis, we can use the shell method. The formula for the volume of a solid of revolution about the \( y \)-axis is: \[ V = 2\pi \int_{a}^{b} x \cdot f(x) dx \] In this case, the function is \( f(x) = x^3 \), and the limits of integration are from \( x = 0 \) to \( x = 2 \). Let's calculate the volume using the shell method. Evaluate the integral by following steps: - step0: Evaluate using formulas and rules: \(2\pi \times \int_{0}^{2} x\times x^{3} dx\) - step1: Multiply the terms: \(2\pi \times \int_{0}^{2} x^{4} dx\) - step2: Evaluate the integral: \(2\pi \times \frac{32}{5}\) - step3: Multiply the terms: \(\frac{64}{5}\pi \) - step4: Multiply: \(\frac{64\pi }{5}\) The volume of the solid generated by revolving the region about the \( y \)-axis is \( \frac{64\pi}{5} \) cubic units. (c) Revolving about the line \( x = 4 \): To find the volume of the solid generated by revolving the region about the line \( x = 4 \), we can use the shell method. The formula for the volume of a solid of revolution about the line \( x = a \) is: \[ V = 2\pi \int_{a}^{b} (a - x) \cdot f(x) dx \] In this case, the function is \( f(x) = x^3 \), the line is \( x = 4 \), and the limits of integration are from \( x = 0 \) to \( x = 2 \). Let's calculate the volume using the shell method. Evaluate the integral by following steps: - step0: Evaluate using formulas and rules: \(2\pi \times \int_{0}^{2} \left(4-x\right)x^{3} dx\) - step1: Multiply the terms: \(2\pi \times \int_{0}^{2} \left(4x^{3}-x^{4}\right) dx\) - step2: Evaluate the integral: \(2\pi \times \frac{48}{5}\) - step3: Multiply the terms: \(\frac{96}{5}\pi \) - step4: Multiply: \(\frac{96\pi }{5}\) The volume of the solid generated by revolving the region about the line \( x = 4 \) is \( \frac{96\pi}{5} \) cubic units.

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To find the volume of the solid generated by revolving the region bounded by the curves \( y = x^3 \), \( y = 0 \), and \( x = 2 \) around the \( x \)-axis using the disk method, we have: The volume \( V \) is given by the integral: \[ V = \pi \int_0^2 (x^3)^2 \, dx = \pi \int_0^2 x^6 \, dx \] Calculating the integral: \[ V = \pi \left[ \frac{x^7}{7} \right]_0^2 = \pi \left[ \frac{2^7}{7} - 0 \right] = \frac{128\pi}{7} \] Now, for the \( y \)-axis using the shell method, we can set it up as follows: \[ V = 2\pi \int_0^2 x \cdot (x^3) \, dx = 2\pi \int_0^2 x^4 \, dx \] Calculating the integral gives: \[ V = 2\pi \left[ \frac{x^5}{5} \right]_0^2 = 2\pi \left[ \frac{2^5}{5} - 0 \right] = \frac{64\pi}{5} \] Lastly, for revolving about the line \( x = 4 \) with the shell method, we measure the distance from \( x = 4 \): \[ V = 2\pi \int_0^2 (4 - x)(x^3) \, dx \] Calculating: \[ V = 2\pi \int_0^2 (4x^3 - x^4) \, dx = 2\pi \left[ \frac{4x^4}{4} - \frac{x^5}{5} \right]_0^2 = 2\pi \left[ 16 - \frac{32}{5} \right] = 2\pi \left[ \frac{80 - 32}{5} \right] = \frac{96\pi}{5} \] In summary, the volumes are: (a) \( \frac{128\pi}{7} \), (b) \( \frac{64\pi}{5} \), (c) \( \frac{96\pi}{5} \). In the swirling world of math, knowing the techniques like the disk or shell method is like having a magic wand for creating shapes! Whether you're spinning a lovely cup around the x-axis or crafting a shell for your secret treasures by twisting it around the y-axis, the volume calculations help you master the art of solids. Get creative with your shapes and visualize these beautiful volumes! Don’t forget, even seasoned mathematicians can trip up when setting up these integrals! Always double-check which axis you're revolving around and confirm the limits of integration. Keeping those straight will help you avoid common pitfalls and ensure you’re on the path to victory with your calculations!

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