1. Identifying a Function
Today’s Lesson:
What:
Identifying a Function
Why:
so I can identify a function and become familiar with
basic function vocabulary.
Input
Output

2. What are 4 ways to represent a function?

3. What are 2 ways
to identify a function?

4. Let’s see what you remember
What to expect in this unit . . .
Up to now, you have solved equations with only one variable. In this unit, you will see a type of equation that has TWO variables– an x AND a y !! You will learn that these equations graph as a straight line.
When you hear things like x y and graph Does anything come to mind?? Think about what you learned in 6th grade. What do you think??
COORDINATE PLANE
SOUND FAMILIAR??
In this unit, we will be graphing linear equations on a coordinate plane.
Let’s see what you remember
about plotting points!!!

5. Coordinate plane review:
Label the following parts:
origin
x axis
y axis
Quad I
Quad II
Quad III
Quad IV
Q II y
Q I F A
origin E x B G D C
Q III
Q IV
On the above coordinate plane, plot the following points: A
(2, 3) B
(-3,-1) C
(0, -6) D
(9, -5) E
(-6, 0) F
(-4, 6) G
(4, -4)

6. Essential vocabulary:
Ordered Pair
A name we use for the x and _______ values that make up a point on the coordinate plane. y
Relation
A group of ordered _____________________.
pairs
Function
A special ___________________ of relation where there is one and only one “y” value for every “x” value. (“x” can never repeat)
TYPE
All functions are relations, but
Not all relations are functions!!!

7. Essential vocabulary:
What is the Domain of the
following relation?
{(1,2); (2,3); (3, 4); (4,5)}
_________________________________
3 ways to name “x” and “y”: x y
INPUT
RANGE
INDEPENDENT
OUTPUT
DOMAIN
D = {1, 2, 3, 4}
DEPENDENT
What is the Range of the
following relation?
{(1,3); (2,5); (3, 7); (4,9)}
_________________________________
R = {3, 5, 7, 9}

8. See? An equation with BOTH x and y!!
4 ways to represent a function:
As an equation
y = _____ 1
4x - 2
With
________
“y is equal to the product of 4 and x,
minus two.” 2
WORDS
See? An equation with BOTH x and y!! 3
As a
_______ 4
As a table x y -2 1 2 6 3 __
GRAPH 10

9. How to identify a function . . .
METHOD ONE: Look to see if the “x” values repeat . . .
If there is more than one _______ value that is the same #,
then the relation is ___________ a function! x
NOT
Are the following examples functions? Answer “YES” or “NO”
___________ ) _____________ ) ______________
YES
YES NO x y 3 1 2 x y -5 5 10 15 x y -1 -2 -4 1 2
4) __________ { (-2, 0); (0, 2); (2, 0); (4, 6) }
YES
5) __________ { (-2, 0); (0, 3); (-2, 2 ); (5, 7) } NO

10. METHOD TWO: VERTICAL LINE TEST —
Look at the graph of the function. If any two points on
the graph can be connected by a ________________ line,
then the relation is NOT a function!
vertical
Are the following examples functions? Answer “YES” or “NO”
______ ) ______
3) ______ ) ______
YES NO
YES NO

11. Wrap it up/Summary: 1) What are 4 ways to represent a function?
2) What are 2 ways you can identify a function?
Equations
Words
Table
Graph
-Look to see if the “x” values repeat. “x” can never repeat!
-Vertical Line Test

12. “Is it a Function?” Worksheet
Homework/ practice Due by next class!
“Is it a Function?” Worksheet

13. END OF LESSON