Math Problem Statement

Solve the following composite function problems: 1. (f ∘ g)(x) with f(x) = 4x - 5 and g(x) = x^2 + 4 2. (g ∘ f)(x) with f(x) = 4x - 5 and g(x) = x^2 + 4

Solution

Let's solve the problems given in the image.

The functions provided are:

  • f(x)=4x5f(x) = 4x - 5
  • g(x)=x2+4g(x) = x^2 + 4

We are asked to compute the following:

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

This means we need to substitute g(x)g(x) into f(x)f(x).

f(g(x))=f(x2+4)=4(x2+4)5f(g(x)) = f(x^2 + 4) = 4(x^2 + 4) - 5 =4x2+165= 4x^2 + 16 - 5 =4x2+11= 4x^2 + 11

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

This means we need to substitute f(x)f(x) into g(x)g(x).

g(f(x))=g(4x5)=(4x5)2+4g(f(x)) = g(4x - 5) = (4x - 5)^2 + 4 =(16x240x+25)+4= (16x^2 - 40x + 25) + 4 =16x240x+29= 16x^2 - 40x + 29

So the answers are:

  • (fg)(x)=4x2+11(f \circ g)(x) = 4x^2 + 11
  • (gf)(x)=16x240x+29(g \circ f)(x) = 16x^2 - 40x + 29

Would you like any further details or explanations?

Here are some related questions for practice:

  1. What is (ff)(x)(f \circ f)(x) if f(x)=4x5f(x) = 4x - 5?
  2. What is (gg)(x)(g \circ g)(x) if g(x)=x2+4g(x) = x^2 + 4?
  3. If f(x)=2x+3f(x) = 2x + 3 and g(x)=x21g(x) = x^2 - 1, what is (fg)(x)(f \circ g)(x)?
  4. How would you find f(x+1)f(x + 1) for f(x)=4x5f(x) = 4x - 5?
  5. How does the result of (gf)(x)(g \circ f)(x) change if g(x)=x24g(x) = x^2 - 4?

Tip: When dealing with composite functions, always apply the inner function first, then the outer function.

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Math Problem Analysis

Mathematical Concepts

Algebra
Composite Functions
Quadratic Expressions

Formulas

f(g(x)) = f(expression)
g(f(x)) = g(expression)

Theorems

Order of operations
Composite function application

Suitable Grade Level

Grade 10-12