# AA Notes 2.1 and 2.2

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.## If a relation is a function, each input has ONLY 1 OUTPUT!

## This relation is NOT A FUNCTION. Slide to see why.

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