Texas Instruments TI-89 Titanium User Manual page 402

You can use the
Note:
equations.
When entering equations in the Y= Editor, do not use
example:
Enter: y1' = .001y1ù(100Ny1)
Not: y1' = .001y1(t)ù(100Ny1(t))
Only 1st-order equations can be entered in the Y= Editor. To graph 2nd- or higher-order
equations, you must enter them as a system of 1st-order equations.
Detailed information is available on setting initial conditions.
Selecting Differential Equations
†
You can use to select a differential
equation, but not its initial condition.
Selecting y1' will graph the y1 solution curve, not the derivative y1', depending
Important:
on the axis setting.
Differential Equation Graphing
command from the Home screen to define functions and
Define
Do not use implied multiplication between a
variable and parenthetical expression. If you
do, it is treated as a function call.
formats to refer to results. For
y(t)
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