Math Problem Statement

Let f(x) = 1 / (x - 2) and g(x) = 4x + 7. Find (f ∘ g)(3) and (f ∘ g)(x).

Solution

Let's work through the problem shown in the image.

We are given:

  • f(x)=1x2f(x) = \frac{1}{x - 2}
  • g(x)=4x+7g(x) = 4x + 7

We need to find:

  1. (fg)(3)(f \circ g)(3)
  2. (fg)(x)(f \circ g)(x)

Solution for (fg)(x)(f \circ g)(x)

The composition (fg)(x)(f \circ g)(x) means f(g(x))f(g(x)). We first substitute g(x)g(x) into f(x)f(x):

(fg)(x)=f(g(x))=f(4x+7)(f \circ g)(x) = f(g(x)) = f(4x + 7)

Substituting 4x+74x + 7 into f(x)=1x2f(x) = \frac{1}{x - 2}:

f(4x+7)=1(4x+7)2=14x+5f(4x + 7) = \frac{1}{(4x + 7) - 2} = \frac{1}{4x + 5}

So, (fg)(x)=14x+5(f \circ g)(x) = \frac{1}{4x + 5}.

Solution for (fg)(3)(f \circ g)(3)

Now, let's calculate (fg)(3)(f \circ g)(3):

  1. First, find g(3)g(3):

g(3)=4(3)+7=12+7=19g(3) = 4(3) + 7 = 12 + 7 = 19

  1. Next, substitute 19 into f(x)f(x):

f(19)=1192=117f(19) = \frac{1}{19 - 2} = \frac{1}{17}

So, (fg)(3)=117(f \circ g)(3) = \frac{1}{17}.

Summary

  • (fg)(3)=117(f \circ g)(3) = \frac{1}{17}
  • (fg)(x)=14x+5(f \circ g)(x) = \frac{1}{4x + 5}

Would you like any further explanation or details on how the function composition works?

Here are 5 related questions for further exploration:

  1. What is the domain of (fg)(x)(f \circ g)(x)?
  2. How would you find (gf)(x)(g \circ f)(x) using the given functions?
  3. What happens to (fg)(x)(f \circ g)(x) if f(x)f(x) or g(x)g(x) is modified?
  4. How can you determine whether (fg)(x)(f \circ g)(x) has any vertical asymptotes?
  5. What is the inverse of (fg)(x)(f \circ g)(x), if it exists?

Tip: Remember that the domain of a composition function is determined by the domain of g(x)g(x) and any additional restrictions imposed by f(x)f(x) after substituting g(x)g(x).

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Math Problem Analysis

Mathematical Concepts

Function Composition
Algebra
Rational Functions

Formulas

(f ∘ g)(x) = f(g(x))

Theorems

Function Composition

Suitable Grade Level

Grades 10-12