HP 40gs - Manual (Page 217)

Computer Algebra System (CAS) 14-35
LDEC Linear differential equations having constant
coefficients
LDEC enables you to directly solve linear differential
equations having constant coefficients.
The parameters are the second member and the
characteristic equation.
Solve:
y” − 6 · y’ + 9 · y = x · e 3·x
Typing:
LDEC(X·EXP(3·X),X 2 −6·X+9)
gives:
cC0 and cC1 are integration constants (y(0) = cC0 and
y’(0) = cC1).
LINSOLVE Solve linear system
LINSOLVE enables you to solve a system of linear
equations.
It is assumed that the various equations are of the form
expression = 0.
LINSOLVE has two arguments: the first members of the
various equations separated by AND, and the names of
the various variables separated by AND.
Example 1
Typing:
LINSOLVE(X+Y+3 AND X-Y+1, X AND Y)
gives:
(x = −2) AND (y = −1)
or, in Step-by-step mode (CFG, etc.):
L2=L2−L1
ENTER
-
18 x 6 – ⋅ ( ) cC0 6 x cC1 ⋅ ⋅ x
3
+ ( ) – ⋅
6
----------------------------------------------------------------------------------------- 3 x ⋅ ( ) exp ⋅
⎝ ⎠
⎛ ⎞
1 1 3
1 1
– 1
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