Press the "ON" button to turn on the Ti-84 graphing calculator.
Press the "VARS" button in the upper-right corner of the calculator.
Select "1:Window" from the X/Y secondary menu.
Scroll down and select delta X, which looks like a triangle with the letter X next to it.
Enter a numerical value for delta X and press the "Enter" button. The built-in formula for delta X is "(Xmax - Xmin)/94." This defines the distance on a graph between the center of two adjacent pixels. The value of "Xmax" will change when you define a value for delta X.