Math Problem Statement

Find left parenthesis f circle g right parenthesis left parenthesis x right parenthesis and left parenthesis g circle f right parenthesis left parenthesis x right parenthesis. ​f(x)equals2 x squared minus 6​, ​ g(x)equals3 x Question content area bottom Part 1 left parenthesis f circle g right parenthesis left parenthesis x right parenthesisequals    enter your response here ​(Simplify your​ answer.)

Solution

To find (fg)(x)(f \circ g)(x) and (gf)(x)(g \circ f)(x), we are working with function composition. Let’s solve each step by step.

We are given:

  • f(x)=2x26f(x) = 2x^2 - 6
  • g(x)=3xg(x) = 3x

Part 1: (fg)(x)(f \circ g)(x)

By definition, (fg)(x)=f(g(x))(f \circ g)(x) = f(g(x)).
Here’s how we proceed:

  1. Start with g(x)g(x): g(x)=3xg(x) = 3x

  2. Substitute g(x)g(x) into f(x)f(x), which is f(u)=2u26f(u) = 2u^2 - 6. Replace uu with g(x)=3xg(x) = 3x: f(g(x))=2(3x)26f(g(x)) = 2(3x)^2 - 6

  3. Simplify: f(g(x))=2(9x2)6f(g(x)) = 2 \cdot (9x^2) - 6 f(g(x))=18x26f(g(x)) = 18x^2 - 6

Thus: (fg)(x)=18x26(f \circ g)(x) = 18x^2 - 6


Part 2: (gf)(x)(g \circ f)(x)

By definition, (gf)(x)=g(f(x))(g \circ f)(x) = g(f(x)).
Here’s how we proceed:

  1. Start with f(x)f(x): f(x)=2x26f(x) = 2x^2 - 6

  2. Substitute f(x)f(x) into g(x)g(x), which is g(u)=3ug(u) = 3u. Replace uu with f(x)=2x26f(x) = 2x^2 - 6: g(f(x))=3(2x26)g(f(x)) = 3(2x^2 - 6)

  3. Simplify: g(f(x))=32x236g(f(x)) = 3 \cdot 2x^2 - 3 \cdot 6 g(f(x))=6x218g(f(x)) = 6x^2 - 18

Thus: (gf)(x)=6x218(g \circ f)(x) = 6x^2 - 18


Final Answer:

  1. (fg)(x)=18x26(f \circ g)(x) = 18x^2 - 6
  2. (gf)(x)=6x218(g \circ f)(x) = 6x^2 - 18

Do you want a step-by-step breakdown of how I substituted and simplified? Let me know!

Related Questions:

  1. What is the difference between (fg)(x)(f \circ g)(x) and (gf)(x)(g \circ f)(x)?
  2. How do you find the domain of (fg)(x)(f \circ g)(x)?
  3. If h(x)=x2+2h(x) = x^2 + 2, what is (hg)(x)(h \circ g)(x)?
  4. How does composition of functions relate to transformations of graphs?
  5. Can (fg)(x)(f \circ g)(x) ever equal (gf)(x)(g \circ f)(x) for certain functions?

Tip: Always substitute one function completely into the other before simplifying!

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Math Problem Analysis

Mathematical Concepts

Function Composition
Simplification of Expressions
Algebra

Formulas

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

Theorems

Definition of Function Composition

Suitable Grade Level

Grades 9-11