Functions - Recognize and Evaluate

                     Lesson 1

 

In math, a relation is just a set of ordered pairs.

{ } are the symbol for "set"

 

 

Function:  A function is a set of ordered pairs in which each element of the domain has only ONE element associated with it in the range.

In mathematics, what distinguishes a function from a relation is that each x value in a function has one and only one y-value.

 

                                                            Problem:    A function is represented by f (x) = 2x + 20.Find f (10).

                                                            

                                                            Solution     To find f (10), replace the x-value with 10.               

                                                            Step 1:                                                                                                                                                             

                     

                                                            Solution     f (10) = 2(10) + 20 = 20 + 20 = 40.

                                                            Step 2:                            

                                                                                         

                                                            Solution     The answer: 40 is called the image of 10 under f (x).

Step 3:                                                            

Complete                                                                   

                                                                                                                               

                                                             Try two practice problems:  

 

                                                                                Solve the following:                                                                                    

 

            A.

Given f(x) = 2x2 - 7x,

find f(4).

B.

Given f(x) = 2x2 - 12x,

find f(8).

 

 

 

 

 

 

 

        

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