8. If f(r) = x" cosh a, find f"(x).

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 8:** If \( f(x) = x^{\pi} \cosh x \), find \( f''(x) \).

**Solution:**

To find the second derivative \( f''(x) \), we start by finding the first derivative \( f'(x) \).

1. **First Derivative (\( f'(x) \))**:
   - \( f(x) = x^{\pi} \cosh x \)
   - Here, we need to apply the product rule: \( (uv)' = u'v + uv' \), where \( u = x^{\pi} \) and \( v = \cosh x \).

   - Derivatives:
     - \( u' = \pi x^{\pi-1} \)
     - \( v' = \sinh x \)

   - Applying the product rule:
     \[
     f'(x) = (\pi x^{\pi-1}) \cosh x + (x^{\pi}) \sinh x
     \]

2. **Second Derivative (\( f''(x) \))**:
   - Differentiate \( f'(x) \) again using the product rule on each term:

   - For \( (\pi x^{\pi-1} \cosh x) \):
     - Apply product rule:
       \[
       \left(\pi x^{\pi-1}\right)' = \pi(\pi-1)x^{\pi-2}
       \]
       \[
       ( \pi(\pi-1)x^{\pi-2} ) \cosh x + (\pi x^{\pi-1}) \sinh x
       \]

   - For \( (x^{\pi} \sinh x) \):
     - Apply product rule:
       \[
       (x^{\pi})' = \pi x^{\pi-1}
       \]
       \[
       (\pi x^{\pi-1}) \sinh x + (x^{\pi}) \cosh x
       \]

   - Combine terms:
     \[
     f''(x) = [\pi(\pi-1)x^{\pi-2} \cosh x + \pi x^{\pi-1} \sinh x] + [\pi x^{\pi-1} \sinh x
Transcribed Image Text:**Problem 8:** If \( f(x) = x^{\pi} \cosh x \), find \( f''(x) \). **Solution:** To find the second derivative \( f''(x) \), we start by finding the first derivative \( f'(x) \). 1. **First Derivative (\( f'(x) \))**: - \( f(x) = x^{\pi} \cosh x \) - Here, we need to apply the product rule: \( (uv)' = u'v + uv' \), where \( u = x^{\pi} \) and \( v = \cosh x \). - Derivatives: - \( u' = \pi x^{\pi-1} \) - \( v' = \sinh x \) - Applying the product rule: \[ f'(x) = (\pi x^{\pi-1}) \cosh x + (x^{\pi}) \sinh x \] 2. **Second Derivative (\( f''(x) \))**: - Differentiate \( f'(x) \) again using the product rule on each term: - For \( (\pi x^{\pi-1} \cosh x) \): - Apply product rule: \[ \left(\pi x^{\pi-1}\right)' = \pi(\pi-1)x^{\pi-2} \] \[ ( \pi(\pi-1)x^{\pi-2} ) \cosh x + (\pi x^{\pi-1}) \sinh x \] - For \( (x^{\pi} \sinh x) \): - Apply product rule: \[ (x^{\pi})' = \pi x^{\pi-1} \] \[ (\pi x^{\pi-1}) \sinh x + (x^{\pi}) \cosh x \] - Combine terms: \[ f''(x) = [\pi(\pi-1)x^{\pi-2} \cosh x + \pi x^{\pi-1} \sinh x] + [\pi x^{\pi-1} \sinh x
Expert Solution
Step 1

Given:-

f(x) =xπ coshx 

To find:-

f''(x) 

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