Exercise 3 Page 169

For a relation to be a function, each $x\text{-}$value can only be paired with one $y\text{-}$value, but one $y\text{-}$value can be paired with multiple $x\text{-}$values. Let's consider the given relation. This means that for every value of $y,$ the value of $x$ is $\text{-}2.$ The given relation does not meet the definition of a function. Therefore, $x=\text{-}2$ is not a function.