Which of the relations given by the following sets of ordered pairs is not a function?
1) (5,0), (4,0), (3,0), (2.0), (1,0)
2) (-4, - 2), (-1, - 1), (- 1, 1), (3,5), (7, 10)
3) (-8,3), (- 6,5), ( – 4,2), ( – 2,7), ( – 1,4)
4) (-6, 4), ( – 3. – 2), (0,5), (1, - 2), (2,3)
