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TI89 WORKSHEET 5:Algebra Concepts
The TI89 can graph many different types of
equations. The following four examples
illustrate different types of equations graphed
on the TI89. In these examples, the function
must be rewritten to be a function of x. The
examples demonstrate how to use the solve
feature of the calculator to rewrite the function
before graphing.
Example 1:
Graph the following equation.
3y – 9x = 15
First, change from standard form to slope intercept
form by using the solve function :
Step 1: Press „ followed by 1 to access the
“solve(” function and press ¸.
Step 2: Type in the above equation and then
push the enter key. ¸.
Step 3:
Enter the above equation into the
yeditor for y1=. (If you know how to copy and
paste, this process can be simplified )
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 yeditor 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 yeditor to the
graphing screen.
Step 5: Graph the equation.
Example 2: Graph the following equation
y = x^{2} + 2x − 4
Step 1:
Enter the above equation into the
yeditor for y2=.
Step 2: Highlight y1 and press
This will
remove the check mark and instruct the
calculator to only graph y2.
Step 3: Graph the equation.
Example 3: Graph the following equation
First, this must be written as a function of x.
Therefore it must be solved for y .
Step 1: From the home screen select
Step 2: Type in the equation. Type in a
comma and then a y. Finish by typing a close
parenthesis and press enter.
Step 3: Use your arrow keys to highlight the
answer. Press
to copy the answer.
Step 4: Press
to access the equation
editor screen. Using
paste the
answer in y1. The answer will appear in the
entry line . It is important that the extra y= is
deleted before you hit enter.
Step 5: Graph the equation.
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