+130511 This is not a function because it doesn't pass the vertical line test. Notice that if y = -1, then x = 1. And if y = 1, x =1. So the points (1, -1) and (1, 1) are on the graph. But the same x value can't have two y values associated with it, since the vertical line x = 1 would go through both points.
+130511 This is not a function because it doesn't pass the vertical line test. Notice that if y = -1, then x = 1. And if y = 1, x =1. So the points (1, -1) and (1, 1) are on the graph. But the same x value can't have two y values associated with it, since the vertical line x = 1 would go through both points.
