Math Problem Statement

Find (g ∘ f)(x) and (f ∘ g)(x) for the given functions f and g. f(x) =

x + 5 , g(x) = 1 x (g ∘ f)(x) =

(f ∘ g)(x) =

Solution

To find (gf)(x)(g \circ f)(x) and (fg)(x)(f \circ g)(x), we need to compute the compositions of the functions f(x)=x+5f(x) = x + 5 and g(x)=1xg(x) = \frac{1}{x}.

1. Finding (gf)(x)(g \circ f)(x):

(gf)(x)=g(f(x))(g \circ f)(x) = g(f(x)) This means we substitute f(x)f(x) into g(x)g(x).

  1. Start with f(x)=x+5f(x) = x + 5.
  2. Substitute x+5x + 5 into g(x)=1xg(x) = \frac{1}{x}: g(f(x))=g(x+5)=1x+5g(f(x)) = g(x + 5) = \frac{1}{x + 5}

Therefore, (gf)(x)=1x+5(g \circ f)(x) = \frac{1}{x + 5}

2. Finding (fg)(x)(f \circ g)(x):

(fg)(x)=f(g(x))(f \circ g)(x) = f(g(x)) This means we substitute g(x)g(x) into f(x)f(x).

  1. Start with g(x)=1xg(x) = \frac{1}{x}.
  2. Substitute 1x\frac{1}{x} into f(x)=x+5f(x) = x + 5: f(g(x))=f(1x)=1x+5f(g(x)) = f\left(\frac{1}{x}\right) = \frac{1}{x} + 5

Therefore, (fg)(x)=1x+5(f \circ g)(x) = \frac{1}{x} + 5

Summary:

(gf)(x)=1x+5(g \circ f)(x) = \frac{1}{x + 5}

(fg)(x)=1x+5(f \circ g)(x) = \frac{1}{x} + 5

Would you like more details or have any questions?

Here are 5 related questions:

  1. What are the domains of (gf)(x)(g \circ f)(x) and (fg)(x)(f \circ g)(x)?
  2. How do you find the inverse of a composition of two functions?
  3. What is the range of (gf)(x)(g \circ f)(x)?
  4. Can you find (ff)(x)(f \circ f)(x) and (gg)(x)(g \circ g)(x)?
  5. How do you verify if two functions are inverses of each other?

Tip: When working with function compositions, always check the domains of the individual functions and the composed function to ensure that all values are valid.

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Math Problem Analysis

Mathematical Concepts

Function Composition
Algebra
Inverse Functions

Formulas

(g ∘ f)(x) = g(f(x)) = 1/(x + 5)
(f ∘ g)(x) = f(g(x)) = 1/x + 5

Theorems

Function Composition Theorem
Domain and Range Restrictions

Suitable Grade Level

Grades 9-12