# Basic Algebra/Lines (Linear Functions)/Functions and Relations

## Vocabulary[edit]

## Lesson[edit]

y = x2

Is this a function?

versus, y2 = x

Is this a function?

The first equation is a function because x has only one y-value, whereas the second equation has many values.

In a function, each domain value or x-value should only have one y-value, otherwise it is not a function.

Definition: *In two sets, A and B, a function is a mapping from A to B.*

This mapping should satisfy the following conditions in order for it to be a function:

- All the elements of set A
be paired with any element of set B.**should** - An element of set A
be paired with more than one element of set B. (i.e. the first coordinates of an ordered pairs should not be repeated)**should not**