Math 8: Functions
Section #3: Writing Rules to Represent Functions
Corresponds with Module 5, Lesson 6, 8.F.4
Notes #62
____________________________
Function: a set of _________________ in which each _____________ value (x-value/domain)
corresponds to one and only one ______________ value (y-value/range).
Linear Function: a function with a constant ________________________ between the ordered pairs
and whose graph forms a _______________________.
Example#1: This represents a function expressed in table form. Look for a pattern or relationship
between the x and y values to express the data in a variety of ways.
x
y
-2
-1
-1
0
0
1
1
2
2
3
Verbally: ____________________________________
Algebraically (Rule): __________________________
Graphically: _________ each point and draw a line.
You Try: For each set of data, express the relationship verbally and find the rule that relates x to y.
1)
x
y
0
0
2
6
4
12
6
18
8
24
Rule: ____________________
Verbally: ________________________________________________________________________
2)
x
-2
-1
0
1
2
y
-5
-4
-3
-2
-1
Rule: ____________________
Verbally: ________________________________________________________________________
x
y
3)
-6
3
-2
1
2
-1
6
-3
10
-5
Rule: ____________________
Verbally: ________________________________________________________________________
Example#2: Find the rule for this function.
x
y
0
2
1
4
2
6
3
8
4
10
To Find the Rule for a Function:
1) Look for an _______________ pattern that can be expressed ______________.
2) If you can’t find a pattern, then think of ___________________.
3) Find the ____________________ or _________.
=
change in the
change in the
4) Find the ________________, by substituting in the ___, ___, & ___ values into
y = mx + b and solving for _____.
YOU TRY: Write a rule that defines the function algebraically.
4)
x
y
5)
x
y
-2
-7
2
6
-1
-4
4
9
0
-1
6
12
1
2
8
15
2
5
10
18
Rule: ____________________
Rule: ____________________
Math 8: Functions
Section #3: Writing Rules to Represent Functions
Corresponds with Module 5, Lesson 6, 8.F.4
HW #62
____________________________
1-4 Write a rule that defines each function algebraically.
1)
2)
x
y
x
y
-2
-10
-2
-7
-1
-5
-1
-2
0
0
0
3
1
5
1
8
2
10
2
13
x
y
4)
x y
3
-1
5
6
0
10 5
9
1
15 6
12
2
20 7
15
3
25 8
3)
4
Write a rule that defines each function algebraically. Find the missing values.
5)
6)
x
y
x
y
1
4
-4
3
2
12
-2
1
3
20
0
-1
3
6
76
-9