Math Problem Statement

If f(x) = x - 4 and g(x) = x^2 - 1, what is g(f(x))?

Solution

The image contains a mathematical problem involving functions. Here's the information from the image:

Given:

  • f(x)=x4f(x) = x - 4
  • g(x)=x21g(x) = x^2 - 1

The task is to find g(f(x))g(f(x)), which is the composition of the two functions.

Solution:

  1. First, we know that f(x)=x4f(x) = x - 4.
  2. To find g(f(x))g(f(x)), we substitute f(x)f(x) into g(x)g(x).
  3. The function g(x)=x21g(x) = x^2 - 1, so we replace xx with f(x)f(x): g(f(x))=(f(x))21=(x4)21g(f(x)) = (f(x))^2 - 1 = (x - 4)^2 - 1
  4. Now expand (x4)2(x - 4)^2: (x4)2=x28x+16(x - 4)^2 = x^2 - 8x + 16
  5. Substitute this back into the expression for g(f(x))g(f(x)): g(f(x))=x28x+161=x28x+15g(f(x)) = x^2 - 8x + 16 - 1 = x^2 - 8x + 15

Thus, the correct answer is g(f(x))=x28x+15g(f(x)) = x^2 - 8x + 15.

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Related Questions:

  1. What is the definition of function composition?
  2. How do you expand binomials like (x4)2(x - 4)^2?
  3. How does substitution work when composing functions?
  4. What are some common mistakes when performing function composition?
  5. Can function composition be reversed? If so, how?

Tip:

When performing function composition, always ensure that the result from the inner function is substituted entirely into the outer function.

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Math Problem Analysis

Mathematical Concepts

Function Composition
Substitution
Quadratic Expansion

Formulas

f(x) = x - 4
g(x) = x^2 - 1
g(f(x)) = (x - 4)^2 - 1 = x^2 - 8x + 15

Theorems

Function Composition Theorem

Suitable Grade Level

Grades 9-12