HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010

Example 10: First order linear differential equation
In order to illustrate the use of the CAS help pages discussed on page 361 we will the example provided in
them rather than making one up. The functions available for solving differential equations are
DESOLVE and
LDEC.
Begin by pressing
SHIFT SYNTAX to open the help menu and scroll
down to the DESOLVE function as shown right. Pressing will
jump immediately to the ‘D’s.
ENTER Notice the
will
VIEWS
d1Y(X)
’ is
Pressing
will display the screen shown right.
Press to paste the example into the CAS editing screen. The screen
shot right has been obtained by pressing
and cutting and
pasting in a Paint program to obtain a wider result. The ‘
reference to
LDEC at the bottom of the screen. Pressing
jump to the screen for
LDEC.
used to represent the first derivative.
Highlighting this and pressing
ENTER will give the result shown
right. Note the use of ‘
cC0’ to represent a constant.
x
This is equivalent to
y
=
(
x
−
1
)
e
+
c
. The CAS unfortunately uses
e
x
x
x
EXP(X) to represent e , although it will understand the use of e when entering an expression.
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