Pre-Calculus - Evaluating the composition of functions and then determining the domain

The video tutorial explains how to rewrite G of X as F of G of X, emphasizing the concept of function notation. It discusses the idea of inputs in functions, highlighting that G of X can be treated as a whole input. The tutorial further explains how to insert functions as inputs, using the example of sqrt(X - 3). Finally, it covers domain constraints, noting that the domain must be greater than or equal to 3.

How do you replace X with another expression in a function? Provide an example.

Describe the significance of the domain being from 3 to infinity in the context of the function.