Texas Instruments TI-82 Getting Started page 13

Figure I.33: Y= screen with only
Many different functions can be stored in the Y= list and any combination of them may be graphed
simultaneously. You can make a function active or inactive for graphing by pressing ENTER on its equal
sign to highlight (activate) or remove the highlight (deactivate). Now go back to the Y= screen and do what
is needed in order to graph
Now activate both functions so that both graphs are plotted. Press TRACE and the cursor appears first on
3
the graph of y x
Y , because of the numeral 1 that is displayed in the upper right corner of the screen (see Figure I.30). Press
1
the up or down arrow key to move the cursor vertically to the graph of
2 is displayed in the upper right corner of the screen. Next press the left and right arrow keys to trace along
the graph of y .25x.
from one graph to another with the
Technology Tip: Trace along the graph of
reach the left or right edge of the window. Keep pressing the arrow key and the TI-82 will allow you to
continue the trace by panning the viewing window. Check the WINDOW screen to see that Xmin and Xmax
are automatically updated.
If you trace along the graph of
window. The cursor's coordinates on the graph will still be displayed, though the cursor itself can no longer
be seen. When you are tracing along a graph, press ENTER and the window will quickly pan over so that
the cursor's position on the function is centered in a new viewing window. This feature is especially helpful
when you trace near or beyond the edge of the current viewing window.
The TI-82's display has 95 horizontal columns of pixels and 63 vertical rows. So when you trace a curve
across a graph window, you are actually moving from Xmin to Xmax in 94 equal jumps, each called
would calculate the size of each jump to be
be friendly numbers like 0.1 or 0.25 so that, when you trace along the curve, the
incremented by such a convenient amount. Just set your viewing window for a particular increment
making Xmax = Xmin
5 94 0.3 23.2.
some special y.
To center your window around a particular point,
and Xmax h 47
to center a window around the origin
range so that Xmin 0
and Ymax
7.75, 0
Technology Guide
Graphing
Y active
2
Y but not Y .
1 2
because it is higher up in the Y= list. You know that the cursor is on this function,
4x
When more than one function is plotted, you can move the trace cursor vertically
and keys.
y
3
y x 4x, the cursor will eventually move above or below the viewing
x
94 x. For example, if you want Xmin
Likewise, set Ymax = Ymin
x. Likewise, make Ymin
0, 0), with both horizontal and vertical increments of 0.25, set the
47 0.25 11.75, Xmax
31 0.25 7.75.
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−10
Figure I.34: Graph of
.25x and press and hold either
Xmax Xmin
. Sometimes you may want the jumps to
94
62 y if you want the vertical increment to be
h, k), and also have a certain
k 31 y and Ymax
0 47 0.25
10
10
−10
y .25x
y .25x. Now the numeral
or . Eventually you will
x- coordinates will be
5 and x 0.3, set Xmax
set Xmin =
x, h
k 31 y. For example,
11.75, Ymin 0 31 0.25
x. You
x by
47 x
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