Math Problem Statement

Given the functions f(x) = 2x - 2, g(x) = sqrt(4 - x), and h(x) = 4x - x^2, find the composition (f o g o h)(x).

Solution

We are tasked with solving the composition of three functions, (fgh)(x)(f \circ g \circ h)(x), where:

  • f(x)=2x2f(x) = 2x - 2
  • g(x)=4xg(x) = \sqrt{4 - x}
  • h(x)=4xx2h(x) = 4x - x^2

To find (fgh)(x)(f \circ g \circ h)(x), we need to first calculate g(h(x))g(h(x)), then substitute that result into f(x)f(x).

Step 1: Find g(h(x))g(h(x))

Since h(x)=4xx2h(x) = 4x - x^2, we substitute it into g(x)=4xg(x) = \sqrt{4 - x}:

g(h(x))=4(4xx2)=44x+x2=(x2)2=x2g(h(x)) = \sqrt{4 - (4x - x^2)} = \sqrt{4 - 4x + x^2} = \sqrt{(x - 2)^2} = |x - 2|

Thus, g(h(x))=x2g(h(x)) = |x - 2|.

Step 2: Find f(g(h(x)))f(g(h(x)))

Now, we substitute g(h(x))=x2g(h(x)) = |x - 2| into f(x)=2x2f(x) = 2x - 2:

f(g(h(x)))=f(x2)=2x22f(g(h(x))) = f(|x - 2|) = 2|x - 2| - 2

For the possible answers, we assume x2x \geq 2, which simplifies x2=x2|x - 2| = x - 2. Therefore:

f(g(h(x)))=2(x2)2=2x42=2x6f(g(h(x))) = 2(x - 2) - 2 = 2x - 4 - 2 = 2x - 6

Final Answer:

The correct answer is e) 2x62x - 6.


Would you like further details on any part of this solution? Here are five related questions to consider:

  1. What happens to f(g(h(x)))f(g(h(x))) if x<2x < 2?
  2. How do we handle function compositions with different domains?
  3. What is the general rule for function composition (fg)(x)(f \circ g)(x)?
  4. Can function compositions be commutative?
  5. How would the composition change if one of the functions was modified?

Tip: Always verify the domain of each function in compositions, especially when dealing with square roots or absolute values.

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Math Problem Analysis

Mathematical Concepts

Function Composition
Absolute Value
Quadratic Functions

Formulas

f(g(h(x)))
sqrt(a-b)
ax^2 + bx + c

Theorems

Composition of Functions

Suitable Grade Level

High School