Math Problem Statement

Find f∘g and the domain. f(x) = x^4, g(x) = (x + 1)^(1/2)

Solution

The problem asks to find fgf \circ g (composition of functions) and the domain, where the functions are:

  1. f(x)=x4f(x) = x^4
  2. g(x)=(x+1)12g(x) = (x + 1)^{\frac{1}{2}} (or the square root of x+1x+1)

Step 1: Find fgf \circ g (composition of functions)

By definition, fg(x)=f(g(x))f \circ g (x) = f(g(x)).

Substitute g(x)=(x+1)12g(x) = (x + 1)^{\frac{1}{2}} into f(x)=x4f(x) = x^4: f(g(x))=((x+1)12)4f(g(x)) = \left( (x + 1)^{\frac{1}{2}} \right)^4 Simplify: f(g(x))=(x+1)2f(g(x)) = (x + 1)^2

So, fg(x)=(x+1)2f \circ g(x) = (x + 1)^2.

Step 2: Determine the Domain

The domain of fgf \circ g depends on both the domain of g(x)g(x) and whether the composition makes sense.

  • The function g(x)=(x+1)12g(x) = (x + 1)^{\frac{1}{2}} (square root function) is only defined when x+10x + 1 \geq 0, which implies: x1x \geq -1

  • The function f(x)=x4f(x) = x^4 is defined for all real numbers, so the domain of the composite function f(g(x))f(g(x)) is the same as the domain of g(x)g(x).

Thus, the domain of fgf \circ g is x1x \geq -1.

Final Answer:

  • fg(x)=(x+1)2f \circ g(x) = (x + 1)^2
  • Domain: x1x \geq -1

Would you like more details on any step or have questions about related concepts?

Here are 5 related questions you might explore:

  1. What is the domain of f(g(x))f(g(x)) if the functions are reversed?
  2. How would the composition change if f(x)f(x) or g(x)g(x) were different types of functions?
  3. What happens to the range of fgf \circ g in this case?
  4. How do you find the domain of a composition of trigonometric functions?
  5. How does the order of function composition affect the result?

Tip: When finding the domain of a composite function, always consider the domains of both functions individually before combining them!

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Math Problem Analysis

Mathematical Concepts

Function Composition
Algebra
Square Roots

Formulas

f ∘ g(x) = f(g(x))
(a^b)^c = a^(b*c)

Theorems

Domain of Composite Functions

Suitable Grade Level

Grades 10-12