Sharp EL-9900 - Manual (Page 94)

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Chapter 6
Advanced Graphing Features
— Advanced Keyboard
In this chapter, some real-life situations are featured. You are encouraged to modify
the examples to make your own graph schemes.
Note: To try the examples in this chapter, it is required that the Advanced Keyboard is
already set up by the user. To learn how to set up the Advanced Keyboard, read
“Changing the Keyboard” in Chapter 1.
It should be noted that the following examples assume that the angle mode is
set to Rad (radian), the default angle unit for the Advanced Keyboard. If set to
degree or gradient, some unexpected results will be obtained.
1. Try it!
You have just opened your own bank
account, with an initial deposit amount of
$2,000. Suppose your monthly income is
$3,000, and you will spend 60 percent of
what you have in the account every month,
how much will your balance be after one
year? How much will you have in the
account, 6 months from now?
The example can be expressed as a sequential equation, as
follows:
u
n
= u
n–1
× (1 – 0.6) + 3000
where u
n
is the balance of the current month and u
n–1
is the
balance of the previous month, and n is the month.