A function is given by a table of values, a graph, a formula, or a verbal description. Determine whether it is one-to-one.
$f(x)$ is not a one-to-one function.
we're deciding whether or not this function is 1 to 1. And to be 1 to 1 means that every X value has only one y value, and every y value has only one X value. And so, if every X value has only one y value, it's going to pass the vertical line test. If you pass a vertical line through, it will pass through no more than one point. So, yes, this one does pass the vertical line test for every Y value to have only one X value, it must pass the horizontal line test. So if you pass a horizontal line through, will it pass through one point and not more than one? Well, some of them do, but then there are others that pass through multiple points. So this fails a horizontal line test. That means this is not a 1 to 1 function