Solution 12081: Graphing Inequalities on the TI-89 Family, TI-92 Family, and Voyage™ 200 Graphing Calculators.
How do I graph inequalities on my TI-89 family, TI-92 family, and Voyage 200 graphing calculators?
The TI-89 family, TI-92 family, and Voyage 200 graphing calculators' Y= Editor does not allow an inequality to be entered into the calculator directly. However, the graph styles feature can be utilized to show the solution set for an inequality. The example below will demonstrate how to graph a simple inequality using these features.
Example: Graph y<=3x+2
On the graphing calculator:
1) Press [Diamond Key] [Y=], and next to y1=, input 3x+2 then press [ENTER].
2) Press the [Up Arrow] once to highlight the "3x+2".
3) Press [2nd] [F1] to open the "Style" menu and press  to select 8:Below.
4) Press [Diamond Key] [F3] to view the shaded graph of the inequality.
Please see the TI-89 family, TI-92 family and Voyage 200 guidebooks for additional information.