Question

Which set of ordered pairs is a function?

{(1,3).(2,4),(3,5),(4,3)}
{(1,3),(1,4),(1,5),(1,3)}
{(2,5),(2,4).(3.4).(4.3)}
{(1,3).(2,8).(3.-6),(1,3)}

Answer 1

{(1,3) (2,4) (3,5) (4,3)}