Hi!
Here is the answer to your question.
Let A and B are two non-empty sets. A function ‘f’ from sets A to set B is a rule or correspondence which associates elements of sets A to elements of set B such that
(a) all elements of set A are associated to elements in set B
(b) an element of set A is associated to a unique element in set B.
The function f from A to B is denoted by f: A → B. Here, A is the domain and B is the co-domain of f.
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