Function Or Not?
Recall the following definitions:
A relation is a correspondence between 2 sets.
Algebraically, you can think of a relation as a set of ordered pairs (x,y).
Once special type of relation is called a FUNCTION.
Every function is a relation, but not every relation is a function.
A function is a relation for which each and every input gets mapped to ONE and ONLY ONE output.
The following applets help further illustrate this concept for functions represented graphically.