What is a composite function and how are they written?

A composite function is a function made from two (or more) other functions. You get it by substituting the x from one expression with the y from another. Functions are usually denoted by letters f, g, h...

Example:

First function: f(x)

Second function: g(x)

Composite: f(g(x)) or g(f(x))

Example with expressions:

f(x) = x²

g(x) = 2x+7

f(g(x)) = (2x+7)²

g(f(x)) = 2x²+7