Use the vertical line test to determine if each relation is a function.
[list=1] [*]Pass a vertical line over the figure in Graph A. Notice that the line crosses two points on the figure at the same time. The relation is not a function. [*]Pass a vertical line over the curve in Graph B. Notice that at any time the vertical line only crosses 1 point on the curve at a time. The relation is a function. [/list] This applet is provided by Walch Education as supplemental material for their mathematics programs. Visit [url="http://www.walch.com"]www.walch.com[/url] for more information on their resources.