Math Problem Statement

Given f(x) = 3x - 2 and g(x) = x^2 + 3x - 4, determine (g ∘ f)(x) and (f ∘ g)(x)

Solution

The problem states:

  1. Given: f(x)=3x2f(x) = 3x - 2 and g(x)=x2+3x4g(x) = x^2 + 3x - 4, determine:

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

Solution:

For function composition, we need to substitute one function into the other.


a. (gf)(x)(g \circ f)(x): This means g(f(x))g(f(x)).

  1. Start with f(x)=3x2f(x) = 3x - 2.
  2. Substitute f(x)f(x) into g(x)=x2+3x4g(x) = x^2 + 3x - 4:

g(f(x))=(3x2)2+3(3x2)4g(f(x)) = (3x - 2)^2 + 3(3x - 2) - 4

Now simplify: =(9x212x+4)+(9x6)4= (9x^2 - 12x + 4) + (9x - 6) - 4 =9x212x+4+9x64= 9x^2 - 12x + 4 + 9x - 6 - 4 =9x23x6= 9x^2 - 3x - 6

So, (gf)(x)=9x23x6(g \circ f)(x) = 9x^2 - 3x - 6.


b. (fg)(x)(f \circ g)(x): This means f(g(x))f(g(x)).

  1. Start with g(x)=x2+3x4g(x) = x^2 + 3x - 4.
  2. Substitute g(x)g(x) into f(x)=3x2f(x) = 3x - 2:

f(g(x))=3(x2+3x4)2f(g(x)) = 3(x^2 + 3x - 4) - 2

Now simplify: =3x2+9x122= 3x^2 + 9x - 12 - 2 =3x2+9x14= 3x^2 + 9x - 14

So, (fg)(x)=3x2+9x14(f \circ g)(x) = 3x^2 + 9x - 14.


Would you like any further explanation on any step?


Here are 5 related questions for further exploration:

  1. How do you graph g(f(x))g(f(x)) and f(g(x))f(g(x))?
  2. What are the domains of g(f(x))g(f(x)) and f(g(x))f(g(x))?
  3. How does the composition of functions differ from addition or multiplication of functions?
  4. Can function compositions be commutative? Why or why not?
  5. What happens if f(x)f(x) or g(x)g(x) have restricted domains or ranges?

Tip: Always pay attention to the domain when composing functions, as the result might be restricted depending on the functions involved.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Function Composition
Algebra

Formulas

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

Theorems

-

Suitable Grade Level

Grades 9-12