Warm-Up Exercises
1. Make a table for y = 2x + 3 with domain 0, 3, 6, and 9.
ANSWER
x
0
3
6
9
y
3
9 15 21
2. Write a rule for the function.
Input, x 0
Output, y 1
ANSWER
y = 3x + 1
2 4 9
7 13 28
Chapter 1.8
Represent Functions as
Graphs
Key Vocabulary
• You can use a graph to represent a function.
Given a table that represents a function, each
corresponding pair of input and output values
forms an ordered pair of numbers that can be
plotted as a point. The x-coordinate is the
input. The y-coordinate is the output.
The horizontal axis of the graph is labeled
with the input variable. The vertical axis is
labeled with the output variable.
Graph a function
• Graph the function y = ½ x with domain 0, 2,
4, 6, and 8.
STEP 1 Make an input-output table.
STEP 2 Plot a point for each ordered pair (x, y).
On Your Own
• Graph the function y = 2x – 3 with domain 2,
3, 4, and 5.
Graph a Function
• The table shows the profit p (in thousands of
dollars) at a small toy store each year from
2000 to 2004 as a function of the time t in
years since 2000. Graph the function.
Closing the Lesson
• How do you represent functions as graphs?
• You can use a graph to represent a function.
• An input-output table can be used to write a
rule for a function whose graph is given.
• You can graph a function by using its domain
and function rule to create an input-output
table, and then by graphing points for each
ordered pair in the table.