Math Problem Statement

Consider the functions f(x) = x + 2 and g(x) = sqrt(x - 3). Determine each of the following: (f ∘ g)(x) and (g ∘ f)(x).

Solution

Let's break down the problem from the image:

Given functions:

  • f(x)=x+2f(x) = x + 2
  • g(x)=x3g(x) = \sqrt{x - 3}

We need to find the compositions:

  1. (fg)(x)=f(g(x))(f \circ g)(x) = f(g(x))
  2. (gf)(x)=g(f(x))(g \circ f)(x) = g(f(x))

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

f(g(x))=f(x3)f(g(x)) = f(\sqrt{x - 3})

Substitute x3\sqrt{x - 3} into f(x)f(x): f(x3)=x3+2f(\sqrt{x - 3}) = \sqrt{x - 3} + 2

So, (fg)(x)=x3+2(f \circ g)(x) = \sqrt{x - 3} + 2

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

g(f(x))=g(x+2)g(f(x)) = g(x + 2)

Substitute x+2x + 2 into g(x)g(x): g(x+2)=(x+2)3g(x + 2) = \sqrt{(x + 2) - 3} =x1= \sqrt{x - 1}

So, (gf)(x)=x1(g \circ f)(x) = \sqrt{x - 1}

Final Composed Functions:

  1. (fg)(x)=x3+2(f \circ g)(x) = \sqrt{x - 3} + 2
  2. (gf)(x)=x1(g \circ f)(x) = \sqrt{x - 1}

Do you want more details or have any questions about these steps?

Here are 5 related questions for further practice:

  1. What is the domain of (fg)(x)(f \circ g)(x) and (gf)(x)(g \circ f)(x)?
  2. How do you find the composition (hf)(x)(h \circ f)(x) for another function h(x)h(x)?
  3. If f(x)=2xf(x) = 2x and g(x)=x2+1g(x) = x^2 + 1, what is (fg)(x)(f \circ g)(x)?
  4. How do you check if two functions are inverses using composition?
  5. Can you compose three functions together, like (fgh)(x)(f \circ g \circ h)(x)?

Tip: When composing functions, always substitute the inner function into the outer function carefully, following the correct order of operations.

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Math Problem Analysis

Mathematical Concepts

Algebra
Function Composition
Square Root Function

Formulas

(f ∘ g)(x) = f(g(x))
(g ∘ f)(x) = g(f(x))
f(x) = x + 2
g(x) = sqrt(x - 3)

Theorems

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Suitable Grade Level

Grades 9-11