Work Step by Step
We know that a function will be one-to-one if each x-value of the function corresponds to only one y-value and each y-value corresponds to only one x-value. We can use the horizontal line test to determine if the given function is one-to-one. This function fails the horizontal line test, because a horizontal line placed between $y=-1$ and $y=-2$ would intersect the graph of the function more than once. In other words, there are y-values that correspond to more than one x-value. Therefore, this function is not one-to-one.