# How do you decide whether the relation #x^2 + y^2 = 25# defines a function?

##### 1 Answer

Nov 1, 2015

A relation is a function if for every **one**

A function can be seen as a recipe, saying if

#### Explanation:

In this case the relation can be rewritten as

These values are only defined in the domain

For the **TWO**

**Extra:**

This relation defines a circle with centre