Math Problem Statement

Orville composed functions f(x)=4x−−√3−2f(x)=4x3−2 and g(x)=(x+24)3g(x)=(x+24)3 to see if the two functions are inverses of each other. His work is shown below.

f∘g=f(g(x))f∘g=f(g(x)) f∘g=f((x+24)3)f∘g=f((x+24)3) f∘g=4(x+24)3−−−−−−√3−2f∘g=4(x+24)33−2 f∘g=4(x+24)−2f∘g=4(x+24)−2 f∘g=(x+2)−2f∘g=(x+2)−2 f∘g=xf∘g=x

Which of the following is true about Orville’s work?

Select THREE correct answers.

A.Orville’s work is correct.

B.Orville’s work is not correct.

C.Orville’s work indicates that the functions are inverses.

D.Orville’s work indicates that the functions are not inverses.

E.The two functions ff and gg are inverses

F.The two functions ff and gg are not inverses.

Solution

To analyze Orville's work and the possible conclusions, let's first review the process for determining if two functions are inverses of each other.

Two functions f(x)f(x) and g(x)g(x) are inverses if and only if:

  1. f(g(x))=xf(g(x)) = x for all xx in the domain of gg,
  2. g(f(x))=xg(f(x)) = x for all xx in the domain of ff.

Orville computed f(g(x))f(g(x)), so let's check that process:

Step 1: Substituting g(x)g(x) into f(x)f(x)

  • Given: f(x)=4x32f(x) = 4\sqrt[3]{x} - 2 and g(x)=(x+24)3g(x) = (x + 24)^3
  • Substituting g(x)=(x+24)3g(x) = (x + 24)^3 into f(x)f(x): f(g(x))=f((x+24)3)=4(x+24)332f(g(x)) = f((x + 24)^3) = 4\sqrt[3]{(x + 24)^3} - 2
  • Simplifying: 4(x+24)33=4(x+24)4\sqrt[3]{(x + 24)^3} = 4(x + 24) f(g(x))=4(x+24)2=4x+962=4x+94f(g(x)) = 4(x + 24) - 2 = 4x + 96 - 2 = 4x + 94

This is not equal to xx, but rather 4x+944x + 94. This means f(g(x))xf(g(x)) \neq x.

Step 2: Conclusion from Orville’s Work

  • Orville claimed that f(g(x))=xf(g(x)) = x, but we have shown that f(g(x))=4x+94f(g(x)) = 4x + 94, so his work is incorrect.
  • Since f(g(x))xf(g(x)) \neq x, the two functions are not inverses.

Correct answers:

  • B: Orville’s work is not correct.
  • D: Orville’s work indicates that the functions are not inverses.
  • F: The two functions ff and gg are not inverses.

Final Answer:

The three correct answers are:

  • B, D, and F.

Do you want further details or explanations on any of the steps?

5 Related Questions:

  1. How can we verify if two functions are inverses using their compositions?
  2. What are common mistakes when checking if two functions are inverses?
  3. How would you compute g(f(x))g(f(x)) in this case?
  4. What are the domain restrictions when dealing with function inverses?
  5. Can two functions be inverses if only one of the compositions equals xx?

Tip:

When checking if two functions are inverses, always check both compositions, f(g(x))f(g(x)) and g(f(x))g(f(x)).

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Math Problem Analysis

Mathematical Concepts

Function Composition
Inverse Functions
Algebra

Formulas

f(g(x)) = 4√3(g(x))−2
g(f(x)) = (f(x) + 24)^3
Inverse function property: f(g(x)) = x and g(f(x)) = x

Theorems

Inverse Function Theorem

Suitable Grade Level

Grades 9-11