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

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This page was edited on 09-Jan-2014