Find the surface area for the object obtained by rotating y=7x+2 about the x-axis over the interval [2,5].

Calculus: Early Transcendentals
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Author:James Stewart
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Chapter1: Functions And Models
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Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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**Problem Statement:**

Find the surface area for the object obtained by rotating \( y = 7x + 2 \) about the x-axis over the interval \([2, 5]\).

**Solution Explanation:**

To find the surface area of a solid of revolution obtained by rotating a function \( y = f(x) \) around the x-axis, we use the formula:

\[ A = 2\pi \int_{a}^{b} f(x) \sqrt{1 + \left( f'(x) \right)^2 } \, dx \]

where:
- \( f(x) \) is the function being rotated,
- \( f'(x) \) is the derivative of \( f(x) \),
- \( [a, b] \) is the interval over which the rotation occurs.

Given \( y = 7x + 2 \):

1. Find the derivative \( f'(x) \):
   \[ f'(x) = 7 \]

2. Substitute \( f(x) \) and \( f'(x) \) into the formula:
   \[ A = 2\pi \int_{2}^{5} (7x + 2) \sqrt{1 + (7)^2} \, dx \]
   \[ = 2\pi \int_{2}^{5} (7x + 2) \sqrt{1 + 49} \, dx \]
   \[ = 2\pi \int_{2}^{5} (7x + 2) \sqrt{50} \, dx \]
   \[ = 2\pi \int_{2}^{5} (7x + 2) \cdot \sqrt{50} \, dx \]
   \[ = 2\pi \sqrt{50} \int_{2}^{5} (7x + 2) \, dx \]

3. Compute the integral:
   \[
   \int_{2}^{5} (7x + 2) \, dx = \left[ \frac{7x^2}{2} + 2x \right]_{2}^{5}
   \]
   Evaluate the definite integral:
   \[
   \left[ \frac{7(5)^2}{2} + 2(5) \right] - \left[ \frac{7(2)^2}{
Transcribed Image Text:**Problem Statement:** Find the surface area for the object obtained by rotating \( y = 7x + 2 \) about the x-axis over the interval \([2, 5]\). **Solution Explanation:** To find the surface area of a solid of revolution obtained by rotating a function \( y = f(x) \) around the x-axis, we use the formula: \[ A = 2\pi \int_{a}^{b} f(x) \sqrt{1 + \left( f'(x) \right)^2 } \, dx \] where: - \( f(x) \) is the function being rotated, - \( f'(x) \) is the derivative of \( f(x) \), - \( [a, b] \) is the interval over which the rotation occurs. Given \( y = 7x + 2 \): 1. Find the derivative \( f'(x) \): \[ f'(x) = 7 \] 2. Substitute \( f(x) \) and \( f'(x) \) into the formula: \[ A = 2\pi \int_{2}^{5} (7x + 2) \sqrt{1 + (7)^2} \, dx \] \[ = 2\pi \int_{2}^{5} (7x + 2) \sqrt{1 + 49} \, dx \] \[ = 2\pi \int_{2}^{5} (7x + 2) \sqrt{50} \, dx \] \[ = 2\pi \int_{2}^{5} (7x + 2) \cdot \sqrt{50} \, dx \] \[ = 2\pi \sqrt{50} \int_{2}^{5} (7x + 2) \, dx \] 3. Compute the integral: \[ \int_{2}^{5} (7x + 2) \, dx = \left[ \frac{7x^2}{2} + 2x \right]_{2}^{5} \] Evaluate the definite integral: \[ \left[ \frac{7(5)^2}{2} + 2(5) \right] - \left[ \frac{7(2)^2}{
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