Example 4: Graph the fol lowing exponential
growth equation y = 4x
Step 1:
Enter the above equation into
y1=.
Step 2: 
Check for an appropriate viewing
window to graph the equation.
Step 3:Press 
Graph the equation.
Problem Set:
1. Graph: y = 3x + 7
2. Graph: ½y = 2x – 3
3. Graph: y = 2x2 + 1
4. Graph: 3y – 12 = x2 – 2x
5. Graph: y = 
GRAPHING INEQUALITIES
It is possible to graph inequalities on the TI -89 by
changing the style settings for the graph before you
plot your function . It is still necessary to solve for y
before you attempt to graph the function, you may
need to do this by hand. You may also consider using
the “solve(“ function of your TI-89. Consider the
following example.
Example: Graph the following inequality: y > 3x − 4
Step 1: 
Enter the right side of the above
equation into y1=.
Step 2: Press 
(which is accessed by pressing
) to choose the style for your graph. Since the
inequality is strictly greater than and not equal to 3x-4
we will choose the dot style. Select 
Step 3: Press 
(which is accessed by pressing
) again. Because our inequality is a “greater
than” choose 
. This will shade everything above the
line.
Choose “7:Above” for > and ≥. Select “8:Below”
for < and ≤.
Step 4: 
Check for an appropriate viewing window
to graph the equation.
You may also consider using the F2 ZOOM tab on
the top of the y-editor screen: 
and
then type 
(alpha =) or press
and scroll
down to option A: in order to select “ZoomFit”,
which establishes a window of best fit for viewing
the graph.
Choosing the “ZoomFit” option will automatically
take you to the graph. Therefore, step 5 is only
necessary to go directly from the y-editor to the
graphing screen.
Step 5: 
Graph the equation.
Problem Set
Graph the following inequalities.
1. y < 2x +1
2. y ≤ 4x − 9
FINDING Y- INTERCEPTS BY GRAPHING
There are multiple ways of finding the y-intercept of a
line on the TI -89. The following example starts with a
line written in standard form and finds the y-intercept
graphically.
Example: Graph the following linear equation .
Then find the y-intercept.
6x + 2y = - 40
First, change from standard form to slope -intercept
form by using the solve function:
Step 1: Press 
1:solve( and press 
Step 2: Type in the above equation and then push the
enter key. 
Step 3: 
Enter the above equation into y1=.
Step 4: 
Graph the equation.
Step 5: Press 
to use the Trace feature to find the
y-intercept
Step 8: Push the zero
key, then push the Enter key.
The coordinates are on the bottom of the screen
denoted as xc for the x-coordinate and yc for the y-coordinate.
Since the y-intercept is the y value when
x =0, this shows the y-intercept is 5.
Problem Set.
Graph each function and find the y-intercept for
each of the following equations:
1. 3y − 2x +15 = 0
2. 1.3x + 2.4y = 3.5
3.
