Question 148812
For it to be a function, there must be a unique 'y' for every 'x'.
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So, in the case of your problem:
[(-4,1),(1,8),(-4,-2)]
[(-4,1),(1,-8),(-2,-2)]
[(-4,1),(1,-8),(1,-2)]
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Set 1: when x=-4 there are two possible y's
Set 3: when x=1 there are two possible y's
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Therefore the only set that can be a function is Set 2.