Math Problem Statement

 Let f(x) = 3x+1 and g(x) = 2-x , Find (f g )(x)

Solution

To find (fg)(x)(f \circ g)(x), which represents the composition of the functions f(x)f(x) and g(x)g(x), we substitute g(x)g(x) into f(x)f(x). This means:

(fg)(x)=f(g(x))(f \circ g)(x) = f(g(x))

We know:

  • f(x)=3x+1f(x) = 3x + 1
  • g(x)=2xg(x) = 2 - x

Now substitute g(x)g(x) into f(x)f(x):

f(g(x))=f(2x)=3(2x)+1f(g(x)) = f(2 - x) = 3(2 - x) + 1

Simplifying:

f(g(x))=3(2)3(x)+1=63x+1=73xf(g(x)) = 3(2) - 3(x) + 1 = 6 - 3x + 1 = 7 - 3x

So, (fg)(x)=73x(f \circ g)(x) = 7 - 3x.

Would you like further details or clarifications? Here are 5 related questions:

  1. How do you compute the composition of two functions?
  2. What happens if you reverse the order of the composition, finding (gf)(x)(g \circ f)(x)?
  3. How do you solve for the domain of a composed function?
  4. Can you determine when f(g(x))=0f(g(x)) = 0?
  5. What is the geometric interpretation of function composition?

Tip: When composing functions, always apply the inner function to the outer function carefully to avoid mistakes in substitution.

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Math Problem Analysis

Mathematical Concepts

Function Composition
Linear Functions

Formulas

(f ∘ g)(x) = f(g(x))

Theorems

Function Composition

Suitable Grade Level

Grades 9-11