Question

Which of the following sets are functions?

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

Answer 1

First set, second set, and fifth set are functions because every x has one and only y.