Relation and Function | Domain and Range | Vertical Line Test

A relation is a set of ordered pairs. A function is a relation in which the x values are unique. Domain is the set of the x values of the ordered pairs in a relation or function. Range is the set of the y values of the ordered pairs in a relation or function. The Vertical Line Test is used to determine whether a given graph represents a function. To perform the vertical line test, simply draw vertical lines anywhere on the graph. If any vertical line has only a single point of intersection with the graph, the graph represents a function. If a vertical line has two or more points of intersection with the graph, the graph does not represent a function.