HP 40gs, Руководство пользователя

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14-34 Computer Algebra System (CAS)
To produce the solutions for y(0) = 1, type:
which gives:
Example 2
Solve:
y” + y = cos(x)
y(0) = 1 y’(0) = 1
It is possible to solve for the constants from the outset.
Typing:
DESOLVE((d1d1Y(X)+Y(X)=COS(X))
AND (Y(0)=1) AND (d1Y(0)=1),Y(X))
gives:
ISOLATE The zeros of an expression
ISOLATE returns the values that are the zeros of an
expression or an equation.
ISOLATE has two parameters: an expression or equation,
and the name of the variable to isolate (ignoring
REALASSUME).
Typing:
ISOLATE(X
4
-1=3,X)
gives in real mode:
(x =
√
2) OR (x =
−√
2)
and in complex mode:
(x =
√
2 · i) OR (x =
−√
2) OR
(x =
−
(
√
2 · i)) OR (x =
√
2)
SUBST Y X
( ) (
cC0
COS
X
( ) ⋅
X 2 + cC1
⋅
2
---------------- +
SIN
X
( )
cC0 ,
⋅
1
)
=
=
y x
( )
2 x
( )
cos
⋅
x 2 + cC 1
⋅ ( )
+ x
( )
sin
⋅
2
---------------------------------------------------------------------------------- =
Y x
( )
x cos
2 x +
2
------------
+ x
( )
sin
⋅
=
hp40g+.book Page 34 Friday, December 9, 2005 1:03 AM