Question 1144960
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In order to judge, is the given mathematical object a function or not, you should have a DEFINITION of this object as a function.


This definition might be DIRECT and EXPLICIT, or clear from a context.


An equation is NOT a definition of a function.  
Even an expression is not a definition of a function, although at some context it might be. 


In the given post, there is NO definition of the function "y", NEITHER explicit NOR from the context.


Therefore, there is no a base to discuss the subject.
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Mathematics <U>is not</U> playing words.