HP 39gII Quick Start Manual page 51

Table 16 Quadratic Explorer App Summary
Summary of Functionality
Press the EQ menu key to enter EQ mode. In this mode, you can change the parameters of
the equation directly and observe the effect on the shape of the graph. The active keys are:
• Use the left- and right-cursor keys to select a parameter
• Use the up- and down-cursor keys to increase and decrease the selected parameter's
value.
• Use the (-) key to change the sign of the parameter a
Press the INCn menu key to toggle through different increment values. Press the EQ menu
key to return to this mode at any time.
Press the TEST menu key to enter the Test view of the app. In the Test view, you can test your
skill at matching an equation to the graph shown. Test view is like EQ mode in that you use
the cursor keys to select and change the value of each parameter in the equation to match
the graph shown. When you are done, press the CHECK menu key to check if your answer
is correct. The menu keys are:
• LEVn: chooses one of four levels of difficulty
• CHECK: checks your current answer against the correct answer
• ANSW: displays the correct answer
• END: returns to the Plot view to explore
The Trig Explorer App
Similar in concept to the Linear and Quadratic Explorers, the Trig Explorer App is a micro-world for exploring the relationship between
the values of parameters in sine or cosine equations and the shapes of their graphs. The forms of the sinusoidal equations used are:
⋅ ( )
y = a sin bx + c + d
⋅ ( )
y = a cos bx + c + d
View Name and Display
EQ Mode
Test View
HP Apps: Solvers and Explorers 45