What does it mean to say that a function f AB is onto What

Solution

In f:A->B ,A is called domain and B is called co-domain.

f : A->B is onto (also known as surjective mapping) :it is mapping from A to B such that for every element in co-domain, there exist at least one element in domain.

Example 1) A B

a --------> 1

b -------> 2

c ------->3

This is onto function

Example:2) A B

a --------> 1

b -------> 2

c ------->3

4

this is not onto mapping because one element of B that is 4 is not mapped with any element in A.