Question

Which relation defined by a set of ordered pairs is a function?
{(2, 6), (3, 6), (4, 5), (6, 6), (7, 6)}
{(6, 2), (6, 3), (5, 4), (6, 6), (7, 6)}
{(2, 6), (3, 6), (4, 5), (6, 6), (6, 7)}
{(–2, 6), (3, –6), (–4, 5), (6, –6), (6, –7)}

Answer 1

{(2,6), (3,6), (4,5), (6,6), (7,6)}
is a function


And another is not
because in remaining set first element is repat so they are not function (according to definition of function)