To determine if a relation is a function, we need to check if each input (the first element of each ordered pair) corresponds to exactly one output (the second element).
Let's examine the given pairs:
- (1, 15)
- (–15, 10)
- (19, 9)
- (9, 19)
Now, we can check the unique inputs:
- The input 1 corresponds to the output 15.
- The input -15 corresponds to the output 10.
- The input 19 corresponds to the output 9.
- The input 9 corresponds to the output 19.
Every input (1, -15, 19, and 9) is unique and each one corresponds to exactly one output.
Since no input is repeated with a different output, we can conclude that this relation is a function.