The graph of f(x) = 2a² + 12z² – 72z + 14 has two horizontal tangents. One occurs at a negative value of z and the other at a positive value of z. What is the negative value of z where a horizontal tangent occurs? What is the positive value of z where a horizontal tangent occurs?

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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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### Horizontal Tangents of a Polynomial Function

#### Problem Description

The graph of the function \( f(x) = 2x^3 + 12x^2 - 72x + 14 \) has two horizontal tangents. One occurs at a negative value of \( x \) and the other at a positive value of \( x \).

- **Question 1:** What is the negative value of \( x \) where a horizontal tangent occurs?
  
  *(Input box for the answer)*

- **Question 2:** What is the positive value of \( x \) where a horizontal tangent occurs?

  *(Input box for the answer)*

#### Explanation

To find where the horizontal tangents occur, we need to find the critical points of the function \( f(x) = 2x^3 + 12x^2 - 72x + 14 \). Critical points occur where the derivative of the function equals zero. So, we calculate the first derivative \( f'(x) \) and solve for \( x \):

1. Find the first derivative \( f'(x) \):

   \[
   f'(x) = \frac{d}{dx} (2x^3 + 12x^2 - 72x + 14)
         = 6x^2 + 24x - 72
   \]

2. Set the derivative equal to zero and solve for \( x \):

   \[
   6x^2 + 24x - 72 = 0
   \]

   Divide through by 6:

   \[
   x^2 + 4x - 12 = 0
   \]

3. Factor the quadratic equation:

   \[
   (x + 6)(x - 2) = 0
   \]

4. Solve for \( x \):

   \[
   x = -6 \quad \text{or} \quad x = 2
   \]

Thus, the negative value of \( x \) where a horizontal tangent occurs is \(-6\), and the positive value is \(2\).
Transcribed Image Text:### Horizontal Tangents of a Polynomial Function #### Problem Description The graph of the function \( f(x) = 2x^3 + 12x^2 - 72x + 14 \) has two horizontal tangents. One occurs at a negative value of \( x \) and the other at a positive value of \( x \). - **Question 1:** What is the negative value of \( x \) where a horizontal tangent occurs? *(Input box for the answer)* - **Question 2:** What is the positive value of \( x \) where a horizontal tangent occurs? *(Input box for the answer)* #### Explanation To find where the horizontal tangents occur, we need to find the critical points of the function \( f(x) = 2x^3 + 12x^2 - 72x + 14 \). Critical points occur where the derivative of the function equals zero. So, we calculate the first derivative \( f'(x) \) and solve for \( x \): 1. Find the first derivative \( f'(x) \): \[ f'(x) = \frac{d}{dx} (2x^3 + 12x^2 - 72x + 14) = 6x^2 + 24x - 72 \] 2. Set the derivative equal to zero and solve for \( x \): \[ 6x^2 + 24x - 72 = 0 \] Divide through by 6: \[ x^2 + 4x - 12 = 0 \] 3. Factor the quadratic equation: \[ (x + 6)(x - 2) = 0 \] 4. Solve for \( x \): \[ x = -6 \quad \text{or} \quad x = 2 \] Thus, the negative value of \( x \) where a horizontal tangent occurs is \(-6\), and the positive value is \(2\).
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