Math Problem Statement

For f(x) = x + 2 and g(x) = 4x + 4, find the following functions: 1. (f ∘ g)(x) 2. (g ∘ f)(x) 3. (f ∘ g)(0) 4. (g ∘ f)(0)

Solution

We are given the functions f(x)=x+2f(x) = x + 2 and g(x)=4x+4g(x) = 4x + 4. We are tasked with finding four composite functions and their values.

Let's go through each part step by step:

a. (fg)(x)(f \circ g)(x)

This represents f(g(x))f(g(x)), meaning we substitute g(x)g(x) into f(x)f(x).

Given:

  • f(x)=x+2f(x) = x + 2
  • g(x)=4x+4g(x) = 4x + 4

Now substitute g(x)g(x) into f(x)f(x): f(g(x))=f(4x+4)=(4x+4)+2=4x+6f(g(x)) = f(4x + 4) = (4x + 4) + 2 = 4x + 6 So, (fg)(x)=4x+6(f \circ g)(x) = 4x + 6.

b. (gf)(x)(g \circ f)(x)

This represents g(f(x))g(f(x)), meaning we substitute f(x)f(x) into g(x)g(x).

Given:

  • f(x)=x+2f(x) = x + 2
  • g(x)=4x+4g(x) = 4x + 4

Now substitute f(x)f(x) into g(x)g(x): g(f(x))=g(x+2)=4(x+2)+4=4x+8+4=4x+12g(f(x)) = g(x + 2) = 4(x + 2) + 4 = 4x + 8 + 4 = 4x + 12 So, (gf)(x)=4x+12(g \circ f)(x) = 4x + 12.

c. (fg)(0)(f \circ g)(0)

This represents f(g(0))f(g(0)).

First, find g(0)g(0): g(0)=4(0)+4=4g(0) = 4(0) + 4 = 4

Now substitute this into f(x)f(x): f(g(0))=f(4)=4+2=6f(g(0)) = f(4) = 4 + 2 = 6 So, (fg)(0)=6(f \circ g)(0) = 6.

d. (gf)(0)(g \circ f)(0)

This represents g(f(0))g(f(0)).

First, find f(0)f(0): f(0)=0+2=2f(0) = 0 + 2 = 2

Now substitute this into g(x)g(x): g(f(0))=g(2)=4(2)+4=8+4=12g(f(0)) = g(2) = 4(2) + 4 = 8 + 4 = 12 So, (gf)(0)=12(g \circ f)(0) = 12.

Final Answers:

  • a. (fg)(x)=4x+6(f \circ g)(x) = 4x + 6
  • b. (gf)(x)=4x+12(g \circ f)(x) = 4x + 12
  • c. (fg)(0)=6(f \circ g)(0) = 6
  • d. (gf)(0)=12(g \circ f)(0) = 12

Would you like more details or have any questions?

Here are 5 related questions for further practice:

  1. What is (ff)(x)(f \circ f)(x) for f(x)=x+2f(x) = x + 2?
  2. What is (gg)(x)(g \circ g)(x) for g(x)=4x+4g(x) = 4x + 4?
  3. How do you find the inverse of the function f(x)=x+2f(x) = x + 2?
  4. How does changing the slope of g(x)g(x) affect (fg)(x)(f \circ g)(x)?
  5. If f(x)f(x) were x2+2x^2 + 2, how would that change (fg)(x)(f \circ g)(x)?

Tip: Always simplify inside the composite function first before applying the outer function.

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Math Problem Analysis

Mathematical Concepts

Function Composition
Algebra

Formulas

(f ∘ g)(x) = f(g(x))
(g ∘ f)(x) = g(f(x))

Theorems

Function composition rules

Suitable Grade Level

Grades 9-12