Math Problem Statement

Suppose H(x) = ∛(7x^2 + 3). Find two functions f and g such that (f ∘ g)(x) = H(x). Neither function can be the identity function.

Solution

The problem asks to express the function H(x)=7x2+33H(x) = \sqrt[3]{7x^2 + 3} as a composition of two functions, f(x)f(x) and g(x)g(x), such that (fg)(x)=H(x)(f \circ g)(x) = H(x). In other words, we need to find two functions where f(g(x))=H(x)f(g(x)) = H(x).

Step-by-Step Breakdown:

  1. We see that H(x)=7x2+33H(x) = \sqrt[3]{7x^2 + 3}. The function involves a cube root applied to 7x2+37x^2 + 3.
  2. One option is to let the inner function g(x)g(x) handle the expression inside the cube root, and let the outer function f(x)f(x) apply the cube root.

So, we can define:

  • g(x)=7x2+3g(x) = 7x^2 + 3 (this is the inner part inside the cube root)
  • f(x)=x3f(x) = \sqrt[3]{x} (this is the cube root part)

Verification:

Now, if we compose f(g(x))f(g(x)), we get: f(g(x))=f(7x2+3)=7x2+33f(g(x)) = f(7x^2 + 3) = \sqrt[3]{7x^2 + 3} which is exactly H(x)H(x).

Thus, the correct functions are:

f(x)=x3,g(x)=7x2+3.f(x) = \sqrt[3]{x}, \quad g(x) = 7x^2 + 3.

Let me know if you need further clarification or details on this solution!

5 Related Questions:

  1. What is the general method for expressing any composite function as two simpler functions?
  2. How do you find the domain of a composite function?
  3. Can you create different pairs of functions f(x)f(x) and g(x)g(x) for the same H(x)H(x)?
  4. How do you differentiate a composite function using the chain rule?
  5. What is the difference between composing functions and multiplying them?

Tip:

Always think of breaking down the function into an "inner" and "outer" function when composing functions. The outer function applies to the result of the inner function.

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Math Problem Analysis

Mathematical Concepts

Composition of functions
Cubic roots
Algebra

Formulas

H(x) = f(g(x))
f(x) = ∛x
g(x) = 7x^2 + 3

Theorems

Function composition

Suitable Grade Level

Grades 9-12