If f(x) = 7+ 3 – 3x², find f'( – 5). -

Calculus: Early Transcendentals
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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

Given the function \( f(x) = 7 + 3x - 3x^2 \), find \( f'(-5) \).

**Solution:**

To find the derivative \( f'(x) \) and subsequently \( f'(-5) \), follow these steps:

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

   \[ f(x) = 7 + 3x - 3x^2 \]
   
   Differentiate each term with respect to \( x \):
   
   \[ f'(x) = \frac{d}{dx}(7) + \frac{d}{dx}(3x) - \frac{d}{dx}(3x^2) \]

   The derivatives of each term are:
   
   - \( \frac{d}{dx}(7) = 0 \) (since the derivative of a constant is zero)
   - \( \frac{d}{dx}(3x) = 3 \) (since the derivative of \( x \) is 1)
   - \( \frac{d}{dx}(3x^2) = 6x \) (since the derivative of \( x^2 \) is \( 2x \), so \( 3 \times 2x = 6x \))

   Combine these results to find \( f'(x) \):
   
   \[ f'(x) = 0 + 3 - 6x \]
   
   Simplify:

   \[ f'(x) = 3 - 6x \]

2. **Find \( f'(-5) \):**

   Substitute \( x = -5 \) into the derivative \( f'(x) \):
   
   \[ f'(-5) = 3 - 6(-5) \]
   
   Calculate the value:
   
   \[ f'(-5) = 3 + 30 \]
   
   \[ f'(-5) = 33 \]

**Solution Summary:**
The derivative of the given function \( f(x) = 7 + 3x - 3x^2 \) is \( f'(x) = 3 - 6x \). Evaluating this derivative at \( x = -5 \), we find that \( f'(-5) = 33 \).
Transcribed Image Text:### Problem Statement Given the function \( f(x) = 7 + 3x - 3x^2 \), find \( f'(-5) \). **Solution:** To find the derivative \( f'(x) \) and subsequently \( f'(-5) \), follow these steps: 1. **Find the first derivative of \( f(x) \):** \[ f(x) = 7 + 3x - 3x^2 \] Differentiate each term with respect to \( x \): \[ f'(x) = \frac{d}{dx}(7) + \frac{d}{dx}(3x) - \frac{d}{dx}(3x^2) \] The derivatives of each term are: - \( \frac{d}{dx}(7) = 0 \) (since the derivative of a constant is zero) - \( \frac{d}{dx}(3x) = 3 \) (since the derivative of \( x \) is 1) - \( \frac{d}{dx}(3x^2) = 6x \) (since the derivative of \( x^2 \) is \( 2x \), so \( 3 \times 2x = 6x \)) Combine these results to find \( f'(x) \): \[ f'(x) = 0 + 3 - 6x \] Simplify: \[ f'(x) = 3 - 6x \] 2. **Find \( f'(-5) \):** Substitute \( x = -5 \) into the derivative \( f'(x) \): \[ f'(-5) = 3 - 6(-5) \] Calculate the value: \[ f'(-5) = 3 + 30 \] \[ f'(-5) = 33 \] **Solution Summary:** The derivative of the given function \( f(x) = 7 + 3x - 3x^2 \) is \( f'(x) = 3 - 6x \). Evaluating this derivative at \( x = -5 \), we find that \( f'(-5) = 33 \).
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