Math Problem Statement

Let f and g be the functions whose graphs are shown below. (a) Find (g ∘ f)(-1). (b) Find (f ∘ g)(4). (c) Find (f ∘ f)(4).

Solution

Let's work through the problem together by analyzing the graph and solving each part:

We have two functions, f(x)f(x) and g(x)g(x), represented by the red and blue curves, respectively. The question involves evaluating composite functions.

(a) Find (gf)(1)(g \circ f)(-1)

This is the composition of the functions, meaning we first evaluate f(1)f(-1), then use that result to find gg at that value.

  1. Find f(1)f(-1): From the graph, when x=1x = -1, the value of f(x)f(x) (red curve) is 11. So, f(1)=1f(-1) = 1.

  2. Now, find g(1)g(1): From the graph, when x=1x = 1, the value of g(x)g(x) (blue curve) is 2-2. Therefore, g(1)=2g(1) = -2.

Thus, (gf)(1)=g(f(1))=g(1)=2(g \circ f)(-1) = g(f(-1)) = g(1) = -2.

(b) Find (fg)(4)(f \circ g)(4)

This is also a composition, meaning we first evaluate g(4)g(4), then use that result to find ff at that value.

  1. Find g(4)g(4): From the graph, when x=4x = 4, the value of g(x)g(x) (blue curve) is 3-3. So, g(4)=3g(4) = -3.

  2. Now, find f(3)f(-3): From the graph, when x=3x = -3, the value of f(x)f(x) (red curve) is 22. Therefore, f(3)=2f(-3) = 2.

Thus, (fg)(4)=f(g(4))=f(3)=2(f \circ g)(4) = f(g(4)) = f(-3) = 2.

(c) Find (ff)(4)(f \circ f)(4)

This composition involves evaluating f(4)f(4), then using that result to find ff at that value.

  1. Find f(4)f(4): From the graph, when x=4x = 4, the value of f(x)f(x) (red curve) is 55. So, f(4)=5f(4) = 5.

  2. Now, find f(5)f(5): From the graph, when x=5x = 5, the value of f(x)f(x) (red curve) is also 55. Therefore, f(5)=5f(5) = 5.

Thus, (ff)(4)=f(f(4))=f(5)=5(f \circ f)(4) = f(f(4)) = f(5) = 5.


Summary of answers:

  • (a) (gf)(1)=2(g \circ f)(-1) = -2
  • (b) (fg)(4)=2(f \circ g)(4) = 2
  • (c) (ff)(4)=5(f \circ f)(4) = 5

Would you like further explanation on any of the steps or additional details?

Related Questions:

  1. What is the value of (fg)(1)(f \circ g)(-1)?
  2. Find (gg)(2)(g \circ g)(2).
  3. How does the composition of functions differ from basic function evaluation?
  4. Can you explain why the graph of a function helps in determining the composition?
  5. How would you solve (fg)(4)(f \circ g)(-4)?

Tip:

When evaluating compositions, always work inside out—start with the innermost function first and use its result for the outer function!

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Math Problem Analysis

Mathematical Concepts

Function Composition
Graph Interpretation
Algebra

Formulas

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

Theorems

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Suitable Grade Level

High School (Grades 9-12)