Question

Which of the following relations is not a function?

{(-1, 3), (4, 2), (-1, 5)}
{(1, 2), (3, -5), (-1, 7)}
{(0, 0), (1, 0), (2, 0)}
{(7, -1), (3, -2), (5, -2)}

Answer 1

keeping in mind that a function has no X-Repeats, namely the 1st coordinate in every pair is never repeated, Check the picture below.