Enter Function; Evaluate Y - Texas Instruments TI-82 Keystroke Manual

14 Calculator Keystroke Guide
page 92

20 Enter Function

See also 16 Window and Default and 18 Graph. To graph an equation, to use an expression
repeatedly for computations, or to generate a table of values of an expression (See 22 Table.)
x − , the expression first needs to be entered in the Y= screen. First press the Y= key
such as 2 3
and erase any old expressions by placing the cursor on the expression to be erased and pressing
CLEAR. Then type 2X−3 to the right of the equal sign next to Y
letter X on the screen is to press the X,T,θ key. To see the graph of this equation, just press the
GRAPH key. The graph will be displayed on the graphing window with the Window settings you
selected. (Refer to 16 Window and Default.) Using the Standard viewing window, you should see
the graph of a straight line as shown below.
Xmin=-10
Xmax=10
Xscl=1
Ymin=-10
Ymax=10
Yscl=1
You may graph up to ten equations on the same graphing window, using the Y= screen to
define the equations to be graphed. (There are ways to produce more than ten graphs on the
graphing window, but we won't discuss that here.) For example, press the Y= key, keep
Y =2X−3, and move the cursor down to the right of the equal sign for Y
1
key to produce the exponent 2.) Thus, you are defining Y
To graph both of these equations, press the GRAPH key. You should see the same straight line as
before, representing the graph of Y
curve that lies almost entirely above the x-axis. It just touches the x-axis at the origin.
Xmin=-10
Xmax=10
Xscl=1
Ymin=-10
Ymax=10
Yscl=1
If you return to the Home screen or turn the calculator off and then back on, the graphs will
still be there to view by pressing the GRAPH key. The graphs will also automatically be displayed
if you press ZOOM 6 to display the Standard (default) viewing window.
page 92

21 Evaluate Y

You can use the Store command to help you evaluate an algebraic expression involving the
variable x. (See 14 Store.) All you need to do is enter the expression on the Y= screen as Y
2
, and you should also then see the graph of Y
1
. The easiest way to produce the
1
and type X
2
to represent y in the equation y
, which is a
2
2 2
. (Use the x
=
2
x .
(or
1