Functions Overview was difficult because it carried the whole volume of Grade 11 with it. Here is an easy lecture. 

Relations define a relationship between input variables and output variables. For and relation to be called a function there can be only one output variable - y for every input variable -x

There are two types of functions

One - to - One

Many - to  - One

We use a Vertical Line test to test that the graph only touches the vertical line once - a function. More than once - not a function

We use the  Horizontal Line Test to test that the graph only touches the horizontal line once - a one-to-one function. More than once -  a many-to-one function

You must be able to identify the Domain and Range of each function or relation

Functions and Relations      

Functions

Revision Discovering Equations    

Functions and Relations   

Meta Calculator

App for plotting graphs                                  

Functions Part 1 - Test  

Functions Part 2 - Test