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HW – pgs. 76-78 (3, 6, 9, . . ., 42)
2.1-2.3 Quiz FRIDAY
www.westex.org HS, Teacher Website
9-24-12
GOAL:
I will be able to:
1. represent relations.
2. determine if a relation is a function.
3. find the domain and range of relations and
functions.
HW – pgs. 76-78 (3, 6, 9, . . ., 42)
2.1-2.3 Quiz FRIDAY
www.westex.org
HS, Teacher Website
Name _________________________
ALG 2 CPA
2.1 Represent Relations and Functions
Definitions:
Date ________
Relation: ________________________________________________
Domain: _________________________________________________
Range: __________________________________________________
Example:
Given the following relation A, state the domain and the
range.
A  (1,5),(3, 2),(2,1),(4, 3),(5,1) 
Domain:
Range:
Another way to show a relation is to use a mapping diagram, which links elements of the domain
with the corresponding elements of the range.
Given:  (4,9),(6,2),(5,9),(3, 4) 
Domain
Range
Make a mapping diagram for the relation  (1, 2),(3,6),(5, 10),(3,2) 
Function: _________________________________________________
_________________________________________________________
Example:
Given the following relations, make a mapping and
determine whether the relation is a function.
1.)
 (1,1),(2,2),(3,5),(4,2) 
2.)
 (1, 2),(2, 0),(1,2),(1,3) 
Graphing a relation on a coordinate plane gives you a visual way to determine whether it is a
function. You can use the ____________ _______ _______.
Graph each set of ordered pairs on the coordinate plane provided. Is the relation a function?
1.)  (5,5),(5, 5),(0,3),(0, 3) 
y
2.)  (4,2),(2, 0),(4,2),(2, 4) 
y
x
x
Use the vertical line test to determine whether each graph represents a function.
Some functions can be represented by equations. The following notation is used to represent a
function described by an equation:
y  2x  1 can be written in function notation as f (x )  2x  1
The symbol f (x ) is read as “f of x” and represents the value of the equation for a particular
element of the domain.
Example:
If f (x )  2x  1 , then f (3) means find the value of the
function when the value of x  3 . The result can be
represented as an ordered pair.
f (3)  2(3)  1  7 So (3,7) is a member of the relation determined
by this function.
Find f (3) , f (0) , and f (5) for each function.
3
f (a )  a  1
1.)
2.)
f (x )  3x  5
4
3.) f (y )  y 2  2y  3
f (3) =
f (3) =
f (3) =
f (0) =
f (0) =
f (0) =
f (5) =
f (5) =
f (5) =
Finding Domain and Range from a Graph
EXIT TICKET
Name _______________________ 9-24-12
A function is a special relation. Explain what this means.
EXIT TICKET
Name _______________________ 9-24-12
A function is a special relation. Explain what this means.
EXIT TICKET
Name _______________________ 9-24-12
A function is a special relation. Explain what this means.
EXIT TICKET
Name _______________________ 9-24-12
A function is a special relation. Explain what this means.
EXIT TICKET
Name _______________________ 9-24-12
A function is a special relation. Explain what this means.