Operation Manual

Chapter 17: Activities 309

7. Press r.

Notice that the values of Y7 and Y8 are zero where the inequality is false. You only see the

intervals of the graph where Y4<Y5 because intervals that are false are multiplied by 0 (Y6†Y4 and

Y6†Y5)

Solving a System of Nonlinear Equations

Problem

Using a graph, solve the equation x

N2x=2cos(x). Stated another way, solve the system of two equations

and two unknowns: y = x

N2x and y = 2cos(x). Use ZOOM factors to control the decimal places displayed

on the graph and use y /

5:intersect to find an approximate solution.

Procedure

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.