how to determine if a set of values is a function?

Question

mayankdevnani · Answer

lets take an example :-
Given Set is :- 0,2,4,6,8,10,12

So we can write it as :-
$$\large \bf x=[{x:x~is~even \space ~NATURAL~number~where ~x \le 12}]$$

mayankdevnani · Answer

hope you understand?  @lyssaaaa

anonymous · Answer

yes i get it but i need to write it in sentence form

mayankdevnani · Answer

this form is a sentence form

anonymous · Answer

no like in general not an example :(

mayankdevnani · Answer

oh! i get it

mayankdevnani · Answer

Remember:- Function of any set does not repeat .
OR you can say that  f(x)=y is a function if for every input (x) there is a unique output(y). 

Like :-
the sets are (1,2),(3,4),(5,6) and (7,8)
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If you have this:-
(2,3),(3,5),(2,8) and ((5,9)
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