Question

The following set of ordered pairs is a function: {(1,4),(1,5),(2,6),(2,-8)}

Answer 1

The ordered pairs is not a function

How to know why they are not a function

In a function, each input value (in this case, each x-value) should be associated with only one output value (y-value).

However, in the given set, the input value 1 is associated with two different output values (4 and 5), and the input value 2 is associated with two different output values (6 and -8).

This is against the definition of a function