User's Manual

17-6 Applications
8317APPS.DOC TI-83 international English Bob Fedorisko Revised: 02/19/01 1:00 PM Printed: 02/19/01 1:39 PM
Page 6 of 20
Using a graph, solve the equation X
3
N
2X = 2cos(X). Stated
another way, solve the system of two equations and two
unknowns: Y = X
3
N
2X and Y = 2cos(X). Use
ZOOM
factors
to control the decimal places displayed on the graph.
1. Press
z
. Select the default mode settings. Press
o
.
Turn off all functions and stat plots. Enter the functions.
2. Press
q
4 to select 4:ZDecimal. The display shows
that two solutions may exist (points where the two
functions appear to intersect).
3. Press
q ~
4 to select 4:SetFactors from the
ZOOM
MEMORY
menu. Set XFact=10 and YFact=10.
4. Press
q
2 to select 2:Zoom In. Use
|
,
~
,
}
, and
†
to move the free-moving cursor onto the apparent
intersection of the functions on the right side of the
display. As you move the cursor, notice that the
X and Y
values have one decimal place.
5. Press
Í
to zoom in. Move the cursor over the
intersection. As you move the cursor, notice that now
the
X and Y values have two decimal places.
6. Press
Í
to zoom in again. Move the free-moving
cursor onto a point exactly on the intersection. Notice
the number of decimal places.
7. Press
y
[
CALC
] 5 to select 5:intersect. Press
Í
to
select the first curve and
Í
to select the second
curve. To guess, move the trace cursor near the
intersection. Press
Í
. What are the coordinates of
the intersection point?
8. Press
q
4 to select 4:ZDecimal to redisplay the
original graph.
9. Press
q
. Select
2:Zoom In and repeat steps 4
through 8 to explore the apparent function intersection
on the left side of the display.
Solving a System of Nonlinear Equations
Problem
Procedure