Functions

A function takes an input, applies at least one rule and then produces an output.

The notation of a function is as follows:

$$\text{[Domain]}\to\text{[Co-Domain]} \text{ defined by }f(x)$$

Graphing

If you have the graph of your function, there is an easy way to check if something is an function.

An example of the graphing test.

An example of the graphing test.

Composition

A functional composition of two functions $f,g$ is a function $t$ such that $t=f(g(x))$.