Question

Which function is NOT one to one?

1) {(0,1), (1,2), (2,3), (3,4)}
2) {(0,0),(1,1),(2,2),(3,3)}
3) {(0,1), (1,0), (2,3), (3,2)}
4) {(0,1), (1,0), (2,0), (3,2)}

Answer 1

4) {(0,1), (1,0), (2,0), (3,2)}

Explanation:

One-to-one functions are when there is only one x value for a specific y value.

In function 4) the points (1,0) and (2,0) break the rule.

The y-value 0 has both x values 1 and 2.