www.MathWorksheetsGo.com Functions versus Relations A function is a relation in which each element of the domain maps to exactly on element of the range. I. Model Problems In these examples we will determine if the relation is a function, identify the domain, and identify the range. Example 1: Check the ordered pairs to determine if every x -value maps to exactly one y -value. Domain is the x- values. Range is the y- values Answer: function, , Example 2: Check the ordered pairs to determine if every x -value maps to exactly one y -value. x = 3 maps to both y = 1 and y Domain is the x- values. Range is the y- values Answer: not a function, , Example 3: Is there a value of x that maps to more than one y ? If needed, check with vertical line test. The vertical lines represent x -values. If the lines do not hit the graph more than once the relations are functions. (scale of graph is one) Domain is the x -values. The line continues in both directions. Range is the y -values. The line continues in both directions. Answer: not a function, ,