## Introduction:

In mathematics, function composition is a powerful tool that allows us to combine functions and analyze their resulting behavior. When considering the composition of two functions, such as (g ◦ f)(x), it is essential to understand the domain of the composite function. In this article, we will explore the concept of function composition and determine which description best explains the domain of (g ◦ f)(x).

## Understanding Function Composition:

Function composition involves applying one function to the output of another function. In the case of (g ◦ f)(x), we first evaluate the input, x, using function f, and then use the resulting value as the input for function g. The composition is denoted as (g ◦ f)(x), read as “g composed with f of x.”

## Domain Considerations:

To determine the domain of (g ◦ f)(x), we need to consider the domains of both functions, f(x) and g(x), and their compatibility when composed.

- Domain of f(x): The domain of f(x) represents the set of all valid input values for function f. It is crucial to identify any restrictions or limitations on the values of x that can be used as input for f(x). These restrictions may arise from factors such as square roots, logarithms, or division by zero, which can lead to undefined values or mathematical inconsistencies.
- Compatibility of Domains: For function composition to be valid, the output of f(x) must fall within the domain of g(x). This means that the values obtained from evaluating f(x) should be acceptable inputs for g(x), ensuring that the composition is well-defined.

## Determining the Description:

Given the above considerations, we can now determine which description best explains the domain of (g ◦ f)(x).

- The Intersection of Domains: If the domains of f(x) and g(x) have common elements, the domain of (g ◦ f)(x) will be the intersection of these domains. This means that the valid input values for (g ◦ f)(x) will be those for which both f(x) and g(x) are defined.
- The Restricted Domain: If the domain of f(x) contains any values that are not within the domain of g(x), the domain of (g ◦ f)(x) will be restricted accordingly. The valid input values for (g ◦ f)(x) will exclude any inputs for which g(x) is not defined.

## Conclusion:

Determining the domain of (g ◦ f)(x) involves considering the domains of both functions, f(x) and g(x), and their compatibility when composed. The best description for the domain of (g ◦ f)(x) depends on the relationship between the domains of the individual functions. It could be the intersection of domains if there are common elements, or it may be a restricted domain if there are values in the domain of f(x) that are not within the domain of g(x). By understanding function composition and the implications for domain, we can effectively analyze the behavior of composite functions and make informed mathematical conclusions.