Texas Instruments TITANIUM TI-89 - Manual (Page 432)

Differential Equation Graphing 432
Example Example Example Example
1. Press 3 and set
Graph=DIFF EQUATIONS .
2. Define a system of equations for the 3rd-
order equation.
Rewrite the equation and make the
necessary substitutions.
y''' + 2y'' + 2y' + y =
sin(x)
y''' = sin(x)
N 2y'' N 2y'
N y
y''' = sin(t) N 2y'' N 2y'
N y
y''' = sin(t) N 2y3 N 2y2
N y1
y3' = sin(t) N 2y3 N 2y2
N y1
3. In the Y= Editor ( 8 #), enter the
system of equations.
4. Enter the initial conditions:
yi1=0 , yi2=1 , and yi3=1
Note: t0 is the time at which the initial
conditions occur. By default, t0=0 .
5. Be sure that only y1' is selected. Use †
to deselect any other equations.
Important: The
solution to the y1'
equation is the
solution to the 3rd-
order equation.