{-4, 0, 1, 3}

{-2, 0, 2, 3}

{-4, -2, 0, 1, 2, 3}

{ (0, 0), (2, -4), (3, 3), (-2, 1) }

{12}

{6, 18}

{3, 9, 15, 16}

{13}

No, because the x-value 11 is paired with 5 and 8.

Yes, because each x-value has only one y-value paired with it.

Yes

No

No, because -1 and 4 are pared with 4.

Yes, because every input is paired with exactly one output.

{(4, -5), (0, -1), (-1, 3), (5, 3)}

{(-5, 4), (-1, 0), (3, -1), (3, 5)}

{(5, -4), (1, 0), (-3, 1), (-3, -5)}

{(-4, 5), (0, 1), (1, -3), (-5, -3)}