Question 382526
Does the set of points {(1,2),(3,2),(6,10),(-3,5)} describe a function? How do you know? 
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Yes: All the x-values are different so there
is no question. It is a function.
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If a couple of the x's were the same you would check
to see if the y-values were different for those
equal x's.  If they were, you would not have a function.
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Cheers,
Stan H.