Now press the GRAPH key. You now see the fol-
lowing (Screen 1.2 in the text).
Locating the Graph
Graph y = x
4
−2x
3
+ x
2
+ 10 in the standard viewing
window. If not satisfactory, find another window.
Solution. When we press the Y = key we should still
have y = x
4
−12x
3
+x
2
−2 there. Move the cursor over
the 1 in 12 and press the DEL key. This deletes the
1. (To insert the 1 back, place the blinking cursor over
the 2 in front of x
3
, and press the keys 2nd INS 1 .)
Now move the cursor to the last minus sign and just
write +10 over the −2. If we graph in the standard
viewing window we see nothing! Press the TRACE
key and obtain the following screen.
We notice that the point (0, 10) is on the graph. We
might think to center the viewing window about this
point. So take a screen with dimensions [−10, 10] by
[0, 20] and obtain the following (Screen 1.3 in the text).
Using the ZOOM Feature
ZOOM about the point (0, 10) in the last screen.
Solution. To ZOOM in about (0, 10), first press the
ZOOM key and then the 2 key. Place the cursor at
(0, 10), press ENTER , and you will obtain the follow-
ing (Screen 1.4 in the text).
Deleting a Function
Remove Y
1
= x
4
− 2x
3
+ x
2
+ 10.
Solution. Press the Y = key, place the cursor after
Y
1
=, and then press the CLEAR key.
The Step Size
Set window dimensions so that TRACE will move in
increments of 0.2 for any graph. Also 0.1.
Solution. There are 95 column of pixels of light on the
TI-82. Thus, there are 94 increments across the screen.
Each increment is then of size (Xmax − Xmin)/94. If
we set Xmax = 9.4 and Xmin = −9.4, each increment
will be of size [9.4 −(−9.4)]/94 = 0.2. Try it. If we set
Xmax = 4.7 and Xmin = −4.7, then each increment
will be of size [4.7 − (−4.7)]/94 = 0.1. Try it.
36
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