HP 40gs - Manual (Page 184)

14-2 Computer Algebra System (CAS)
using vectors and matrices. (Vectors and matrices cannot
be entered using the Equation Writer).
To open the Equation
Writer, press the
soft-
key on the menu bar of the
HOME screen.
The illustration at the right
shows an expression being
written in the Equation
Writer. The soft keys on the
menu bar provide access to
CAS functions and
commands.
To leave the Equation Writer, press to return to
the HOME screen. Note that expressions written in the
Equation Writer (and the results of evaluating an
expression) are not automatically copied to the HOME
history when you leave the Equation Writer. (You can,
however, manually copy them to HOME: see page 14-8).
CAS functions are described in detail in “CAS functions
in the Equation Writer” on page 14-9. Chapter 15,
“Equation Writer”, explains in detail how to enter an
expression in the Equation Writer and contains numerous
worked examples of CAS in operation.
An example
To give you an idea of how CAS works, let’s consider a
simple example. Suppose you want to convert C to the
form
where C is and d is a whole
number.
1. Open the Equation Writer by pressing the soft-
key on the HOME screen.
2. Enter the expression for
C.
[Hint: use the keys on
the keyboard as you
would if entering the
expression in HOME. Press the
key twice to select
the entire first term before entering the second term.]
d 5 ⋅ 2 45 20 –
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