How to Enter Inequalities in the Y= Editor

The Inequality Graphing application on the TI-84 Plus graphing calculator can graph certain functions and inequalities defined in the Y= editor. These functions and inequalities are in the form y = f(x), y < f(x), y > f(x),

To define these functions or inequalities, follow these steps:

1. Press [Y=] to access the Y= editor.

   To erase any unwanted functions or inequalities from the Y= editor, use the arrow keys to place the cursor after the equality or inequality symbol in the definition of the unwanted function or inequality and press [CLEAR].

2. Use the arrow keys to place the cursor on the sign of the function or inequality you are defining.

   This is illustrated in the first screen, where an inequality is to be defined in Y₁.

   

3. Press [ALPHA] and press the key under the appropriate equality or inequality symbol.

   The equality and inequality symbols appear at the bottom of the screen only when the cursor is on the equality or inequality symbol appearing to the right of one of the functions Y₁ through Y₉ or Y₀.

4. Press

   

   and enter the definition of the function or inequality.

   The definition of the function or inequality is entered the same way you enter the definition of a function. The third image shows that the inequality

   

   is defined in Y₁.

After defining a function or inequality, you can change the inequality sign in this definition by following Steps 2 and 3.

The graphing style of an inequality is determined by the Inequality Graphing application and cannot be changed. The application does however allow you to change the graphing style of a function.

When you exit the Inequality Graphing application, all inequality signs in the Y= editor are converted to equal signs and the original inequality sign is not reinstated the next time that you run the application.