On this question I already have f'(x) and I solved for f''(x) and its zeros. I am looking for where the graph of f(x)= (x+4) / (sqrt((x^2) + 4)) is increasing the fastest. I found the maximum to be (12-sqrt(320)) / 22 or (12-8*sqrt(5)) / 22, approximately -.26, which is incorr

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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On this question I already have f'(x) and I solved for f''(x) and its zeros. I am looking for where the graph of f(x)= (x+4) / (sqrt((x^2) + 4)) is increasing the fastest. I found the maximum to be (12-sqrt(320)) / 22 or (12-8*sqrt(5)) / 22, approximately -.26, which is incorrect according to my online homework. Can you see where I'm going wrong? Thank you. 

The handwritten mathematical notes detail the differentiation process, likely finding critical points and analyzing maxima or minima for a given function. Here is a transcription and explanation:

1. Given Function:
   \[
   f(x) = (4x + 4)(x^2 + 4)^{-3/2}
   \]

2. Derivative Calculation:
   \[
   f'(x) = (x^2 + 4)^{-3/2} \left[ (4) + (4x + 4)\left(\frac{3}{2}(x^2 + 4)^{-5/2}(2x)\right) \right]
   \]

3. Simplified Derivative:
   \[
   = (x^2 + 4)^{-5/2} \left[ -1(x^2 + 4) + 4x + 4(3x) \right]
   \]
   \[
   = (x^2 + 4)^{-5/2} \left[ -1x^2 + 12x - 4 \right]
   \]

4. Setting \( f'(x) = 0 \):
   \[
   \Rightarrow \, -1x^2 + 12x - 4 = 0
   \]

5. Solving the Quadratic Equation:
   \[
   x = \frac{12 \pm \sqrt{(12)^2 - 4(1)(-4)}}{2(1)} = \frac{12 \pm \sqrt{320}}{2}
   \]

   Approximating the roots:
   \[
   \approx \frac{12 \pm 17.888}{2}
   \]

   Calculation leads to roots:
   \[
   x \approx 3.26
   \]

6. Maximum/Minimum Analysis:
   \[
   x = \frac{12 - 8\sqrt{5}}{22} \rightarrow \text{ thorough simplification shown}
   \]

The mathematics above details the derivative and critical point calculation for the given function, showing detailed steps for solving the quadratic equation derived from the derivative set to zero, indicating a maximum or minimum of the function \( f(x) \).
Transcribed Image Text:The handwritten mathematical notes detail the differentiation process, likely finding critical points and analyzing maxima or minima for a given function. Here is a transcription and explanation: 1. Given Function: \[ f(x) = (4x + 4)(x^2 + 4)^{-3/2} \] 2. Derivative Calculation: \[ f'(x) = (x^2 + 4)^{-3/2} \left[ (4) + (4x + 4)\left(\frac{3}{2}(x^2 + 4)^{-5/2}(2x)\right) \right] \] 3. Simplified Derivative: \[ = (x^2 + 4)^{-5/2} \left[ -1(x^2 + 4) + 4x + 4(3x) \right] \] \[ = (x^2 + 4)^{-5/2} \left[ -1x^2 + 12x - 4 \right] \] 4. Setting \( f'(x) = 0 \): \[ \Rightarrow \, -1x^2 + 12x - 4 = 0 \] 5. Solving the Quadratic Equation: \[ x = \frac{12 \pm \sqrt{(12)^2 - 4(1)(-4)}}{2(1)} = \frac{12 \pm \sqrt{320}}{2} \] Approximating the roots: \[ \approx \frac{12 \pm 17.888}{2} \] Calculation leads to roots: \[ x \approx 3.26 \] 6. Maximum/Minimum Analysis: \[ x = \frac{12 - 8\sqrt{5}}{22} \rightarrow \text{ thorough simplification shown} \] The mathematics above details the derivative and critical point calculation for the given function, showing detailed steps for solving the quadratic equation derived from the derivative set to zero, indicating a maximum or minimum of the function \( f(x) \).
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