Graph the Derivative of a Function on the TI84 Plus
In calculus, you need to graph the derivative of a function in order to find its critical points, which you can do on your TI84 Plus calculator. Just follow these steps:

Enter your functions in the Y= editor.

Use the arrow keys to place your cursor in an open equation in the Y= editor.

Press [MATH][8] to access the nDeriv template.

Press
then press [ALPHA][TRACE] and choose your function, then press the right arrow and
See the first screen. This is a sneaky move. You aren’t using the nDeriv( template to take the derivative at a specific xvalue. Instead, by taking the derivative at x = x, you are taking the derivative at all points where the function is defined.

Press [GRAPH] to display the graph of your function and the derivative of the function.
See the second screen.

Press [2nd][TRACE] to access the Calculate menu.

Press [2] to select the zero option.

If necessary, repeatedly press the up and downarrow keys until the derivative function appears in the border at the top of the screen.
Don’t forget to do this step!

Enter the Lower and Upper Bounds, then a guess and press e.
This is illustrated in the third screen.