Texas Instruments TI-89 - Page 420

Chapter 23: Activities 403
23ACTS.DOC TI-89/TI-92 Plus: Activities (English) Susan Gullord Revised: 02/23/01 1:24 PM Printed: 02/23/01 2:20 PM Page 403 of 26
6. In the Y=Editor, press:
TI
-
89:
¥ Í
TI
-
92 Plus:
¥
F
and set the Graph Format
variables to:
Axes= ON
Labels= ON
Style= HIDDEN SURFACE
7. Graph the modulus surface.
The 3D graph is used to
visually display a picture of the
roots where the surface
touches the xy plane.
8. Use the
Trace
tool to explore
the function values at
x=1
and
y=0
.
9. Use the
Trace
tool to explore
the function values at
x=0
and
y=1
.
10. Use the
Trace
tool to explore
the function values at
x=0
and
y=
ë
1
.
Note that
zc
is zero for each of the function values in steps 7–9. Thus,
the complex zeros 1,
ë
i
,
i
of the polynomial
x
òì
x
ñ
+x
ì
1
can be
visualized with the three points where the graph of the modulus
surface touches the xy plane.
Note: Calculating and
drawing the graph takes
about three minutes.
Summary