Answers

2015-07-15T20:01:21+08:00
 it is not a function. Because I am awesome!!!

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2015-07-15T20:03:23+08:00
Not a function because there must only and exactly one y (1,2,3,4) that corresponds to a given x(0).. 0 is paired to four different range element so it is not a function.
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thanks help me to another question please
sure