About "How to find the domain and range from a relation"

How to find the domain and range from a relation :

Let A and B be any two non empty sets. A function f from A to B is a rule of correspondence that assigns each element x ∊ A to a unique element y ∊ B. We denote y = f (x) to mean y is a function of x.

The set A is called the domain of the function and set B is called the co-domain of the function. Also, y is called the image of x under f and x is called a pre image of y.

The set of all images of elements of A under f is called the range of f .

Note that the range of a function is a subset of its co-domain.

Let us look into some example problems to understand the above concept.

Example 1 :

Which of the following relations are functions from

A = { 1, 4, 9, 16 } to B = { –1, 2, –3, –4, 5, 6 }

In case of a function, write down its domain and range.