How to Draw the Inverse of a Function on the TI84 Plus
The big idea of inverse function is that x and y switch places. Your TI84 Plus calculator has a builtin feature that enables you to “draw” the inverse of a function. Essentially, the calculator is “graphing” (not drawing) the inverse of the function.
However, unlike a graph, you can’t perform a trace or any other type of function evaluation on the drawn inverse. Another reason this term is used may be that the drawn inverse need not be a function.
Follow these steps to draw the inverse of a function:

Enter your functions in the Y= editor.
See the first screen, which has Y_{1} = e^{x}^{ }entered. This function has a mathematically famous inverse, f^{–1}(x) = ln(x).

Press [2nd][MODE] to access the Home screen.

Press [2nd][PRGM][8] to insert the DrawInv function

Press [ALPHA][TRACE] and choose the name of the function you entered.
See the second screen.

Press [ENTER] to display the graph of your function and draw the inverse of your function.
See the third screen.
Enter Y_{2} = ln(x) to doublecheck that the inverse your calculator drew is the natural log function. In the Y= editor, use the leftarrow key and press [ENTER] to change the line style. Then press [GRAPH] and enjoy the show!