2. Find the intervals where f(x) = x + cosx is concave up or concave down on [0, 2Tt]. Find the x and y coordinates of all inflection points on [0, 21|.

Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
Chapter1: Functions And Models
Section: Chapter Questions
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:**
Determine where the function \( f(x) = \frac{1}{2} x^2 + \cos(x) \) is concave up or concave down on the interval \([0, 2\pi]\). Also, find the x and y coordinates of all inflection points within this interval.

**Calculations:**

1. **First Derivative:**
   \[
   f'(x) = x - \sin(x)
   \]

2. **Second Derivative:**
   \[
   f''(x) = 1 - \cos(x)
   \]

3. **Finding Inflection Points:**
   Set \( f''(x) = 0 \):
   \[
   1 - \cos(x) = 0
   \]
   \[
   \cos(x) = 1
   \]
   This occurs at:
   \[
   x = 0, 2\pi \; \text{(within the interval [0, 2π])}
   \]

4. **Test Intervals for Concavity:**
   - Interval \( (0, 2\pi) \)

   Use test points within the intervals to determine concavity:
   - Test point: \(\pi\)
      \[
      f''(\pi) = 1 - \cos(\pi) = 1 - (-1) = 2 \quad \text{(concave up)}
      \]

   - Therefore, \( f(x) \) is concave up on the interval \( (0, 2\pi) \) except at the boundaries \( x = 0 \) and \( x = 2\pi \).

**Graph Explanation:**
The graph on the left-hand side is a plot on a coordinate system with labeled intervals and markings that illustrate the concavity of the function. Critical points such as \( 0, \pi, 2\pi \) are marked on the x-axis. The areas labeled with ‘+’ and ‘-’ indicate regions where the function is concave up and concave down, respectively:

- At \( x = 0 \) and \( x = 2\pi \), the concavity changes, indicating potential inflection points.
- The concavity between these points is evaluated based on \( f''(x) \).

**Conclusion:**
- The inflection points
Transcribed Image Text:**Problem Statement:** Determine where the function \( f(x) = \frac{1}{2} x^2 + \cos(x) \) is concave up or concave down on the interval \([0, 2\pi]\). Also, find the x and y coordinates of all inflection points within this interval. **Calculations:** 1. **First Derivative:** \[ f'(x) = x - \sin(x) \] 2. **Second Derivative:** \[ f''(x) = 1 - \cos(x) \] 3. **Finding Inflection Points:** Set \( f''(x) = 0 \): \[ 1 - \cos(x) = 0 \] \[ \cos(x) = 1 \] This occurs at: \[ x = 0, 2\pi \; \text{(within the interval [0, 2π])} \] 4. **Test Intervals for Concavity:** - Interval \( (0, 2\pi) \) Use test points within the intervals to determine concavity: - Test point: \(\pi\) \[ f''(\pi) = 1 - \cos(\pi) = 1 - (-1) = 2 \quad \text{(concave up)} \] - Therefore, \( f(x) \) is concave up on the interval \( (0, 2\pi) \) except at the boundaries \( x = 0 \) and \( x = 2\pi \). **Graph Explanation:** The graph on the left-hand side is a plot on a coordinate system with labeled intervals and markings that illustrate the concavity of the function. Critical points such as \( 0, \pi, 2\pi \) are marked on the x-axis. The areas labeled with ‘+’ and ‘-’ indicate regions where the function is concave up and concave down, respectively: - At \( x = 0 \) and \( x = 2\pi \), the concavity changes, indicating potential inflection points. - The concavity between these points is evaluated based on \( f''(x) \). **Conclusion:** - The inflection points
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