Trace - Texas Instruments TI-82 Keystroke Manual

through larger values of x. Press the Up Arrow key until the top number is highlighted. Now
watch the screen as you press the Up Arrow key once more. Note that the table has scrolled up
one row. Press the Up Arrow key again to make the table scroll up again. Try it a few more times.
Try holding down the Up Arrow key for a few seconds. Note that the screen scrolls upward. The
first value of x we used was −3. You can scroll back to that starting point by using the Up Arrow
key. Note that if you get −3 to be the top number in the X column, you can continue to press the
Up Arrow key and have the table scroll up, showing more negative values of x. Any time you
want to leave the table and return to the Home screen, just press 2nd [QUIT].
There is yet another way to evaluate an expression on the TI-82 for your own list of values of
x, using the Table feature. Press 2nd [TblSet ] (the second function on the WINDOW key). Ignore the
values of TblMin and ∆Tbl for now, and use the arrow keys to move the blinking cursor to the line
headed Indpnt. Move the cursor over the word Ask and press ENTER. On the line headed Depend
move the cursor over the word Auto and press ENTER.
Now press 2nd [TABLE] (the second function on the GRAPH key) to display a table. Type in any
value of x you want, such as 3 in the example above. Press ENTER to see the value of Y
other Y's you may have) displayed in the table. Choose any other values of x you want and use the
same procedure to evaluate your Y-variables.
page 94

23 Trace

When you have displayed a graph of an equation, you may trace along points on the graph by
using the Trace cursor. For example, clear out any old equations from the Y= screen and enter as
Y the expression
1
which corresponds most closely to the graphing window shown in Figure 2.18 on page 94 in the
text, first press ZOOM 6 to get the Standard (default) viewing window. Then press ZOOM 8, and
with the cross-hair cursor still near the origin, press ENTER to create the desired Integer graphing
window. (You may want to look at the Window settings to see that they are similar to—but not
exactly the same as—those shown in Figure 2.18, which are for a different calculator model.)
To activate the Trace cursor, press the TRACE key. A cursor will appear on the graph of the
equation, and the coordinates of the cursor will appear at the bottom of the screen. To move the
cursor along the graph and display the coordinates of other points on the graph, use the Left and
Right Arrow keys. Unlike the general cursor (see 19 Cursor), the Trace cursor always stays on
the graph and displays only coordinates of points which are on the graph. To turn the Trace
cursor off, press GRAPH.
If more than one graph is displayed, the Trace cursor may be made to trace along each graph
listed on the Y= screen. For example, go to the Y= screen. Keep the expression already entered as
+
x 4 . To get an Integer graphing window (see 17 Integer) on your calculator
TI-82 17
(and any
1