Introduction to Functions The Domain of the function is the x-values of the function, the Range of the function is the y-values of the function. Determine the Domain and Range of the following function. {(0,1),(2,4),(4,7),(6,10),(8,13)} Domain = {0,2,4,6,8} Range = {1,4,7,10,13} A set of points is a function, if and only if, for every value of x there is a “unique” value for y.  In other words, when you look at a set of points, if an x value is repeated then it had better have the same value for y in both places! Determine whether or not the following sets of points are or are not functions.   (A)     {(1,2),(3,5),(4,5),(5,8),(9,1)}               … D = {1,3,4,5,9}  and  R = {1,2,5,8}                                                                         This is a function since no value of x is repeated.   (B)     {(1,2),(3,5),(4,5),(5,8),(1,9)}               … D = {1,3,4,5}  and  R = {2,5,8,9} This is not a function, since x = 1, is paired with both y values of 2 and 9. To evaluate a function at a particular value for x, substitute the value given and calculate. Find f(-1) for the function f(x) = 2x -4. f(x)   = 2x –4 f(-1) = 2(-1) -4 f(-1) =  -2 –4 f(-1)  = -6 Find f(-2) for the function .                                                             General Algebra Tips The views and opinions expressed in this page are strictly those of Mary Lou Baker. The contents of this page have not been reviewed or approved by Columbia State Community College.This page was edited on 09-Jan-2014