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 X3 N 2X = 2cos(X). Stated
another way, solve the system of two equations and two
unknowns: Y = X3N2X 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 EquationsProblem
Procedure