Which of the following relations is a function?
\{(5, - 7), (4, 6), (- 3, 8), (5, 9)\}
\{(2, 3), (- 2, 3), (3, 2), (- 3, - 2)\}
\{(8, - 4), (- 4, 8), (- 4, - 8), (- 8, 4)\}
\{(9, - 1), (- 1, 9), (9, 2), (2, - 1)\}
The relation that represents a function is:
\{(2, 3), (- 2, 3), (3, 2), (- 3, - 2)\}
In this relation, each input (x-value) is associated with only one output (y-value). This meets the definition of a function.