Find the rules for the composite functions fo g and 8x² + 9x + 4; g(x) = x + 7 fog = 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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**Finding Composite Functions**

In order to find the rules for the composite functions \( f \circ g \) and \( g \circ f \), we need to understand their definitions and use the provided functions.

1. **Given Functions:**
   - \( f(x) = 8x^2 + 9x + 4 \)
   - \( g(x) = x + 7 \)

2. **Composite Function \( f \circ g \):**
   - To find \( f \circ g \), we need to substitute \( g(x) \) into \( f(x) \).
   - \( f \circ g = f(g(x)) = f(x + 7) \).

3. **Composite Function \( g \circ f \):**
   - To find \( g \circ f \), we need to substitute \( f(x) \) into \( g(x) \).
   - \( g \circ f = g(f(x)) = g(8x^2 + 9x + 4) \).

**Steps to Find \( f \circ g \):**

- Substitute \( x + 7 \) in place of \( x \) in \( f(x) \):
   \[
   f(x + 7) = 8(x + 7)^2 + 9(x + 7) + 4
   \]
- Simplify the expression:
   \[
   = 8(x^2 + 14x + 49) + 9(x + 7) + 4
   \]
   \[
   = 8x^2 + 112x + 392 + 9x + 63 + 4
   \]
   \[
   = 8x^2 + 121x + 459
   \]

**Thus, \( f \circ g = 8x^2 + 121x + 459 \).**

**Steps to Find \( g \circ f \):**

- Substitute \( 8x^2 + 9x + 4 \) in place of \( x \) in \( g(x) \):
   \[
   g(8x^2 + 9x + 4) = (8x^2 + 9x + 4) + 7
   \]
- Simplify the expression:
   \[
   = 8x^2 + 9
Transcribed Image Text:**Finding Composite Functions** In order to find the rules for the composite functions \( f \circ g \) and \( g \circ f \), we need to understand their definitions and use the provided functions. 1. **Given Functions:** - \( f(x) = 8x^2 + 9x + 4 \) - \( g(x) = x + 7 \) 2. **Composite Function \( f \circ g \):** - To find \( f \circ g \), we need to substitute \( g(x) \) into \( f(x) \). - \( f \circ g = f(g(x)) = f(x + 7) \). 3. **Composite Function \( g \circ f \):** - To find \( g \circ f \), we need to substitute \( f(x) \) into \( g(x) \). - \( g \circ f = g(f(x)) = g(8x^2 + 9x + 4) \). **Steps to Find \( f \circ g \):** - Substitute \( x + 7 \) in place of \( x \) in \( f(x) \): \[ f(x + 7) = 8(x + 7)^2 + 9(x + 7) + 4 \] - Simplify the expression: \[ = 8(x^2 + 14x + 49) + 9(x + 7) + 4 \] \[ = 8x^2 + 112x + 392 + 9x + 63 + 4 \] \[ = 8x^2 + 121x + 459 \] **Thus, \( f \circ g = 8x^2 + 121x + 459 \).** **Steps to Find \( g \circ f \):** - Substitute \( 8x^2 + 9x + 4 \) in place of \( x \) in \( g(x) \): \[ g(8x^2 + 9x + 4) = (8x^2 + 9x + 4) + 7 \] - Simplify the expression: \[ = 8x^2 + 9
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