Solution 11793: Unable to Graph Multiple Functions on the TI-83 Plus Family and TI-84 Plus Family Graphing Calculators.
Why am I unable to graph multiple functions on the TI-83 Plus Family and TI-84 Plus Family graphing calculator?
In order to select additional graphs, the Transformation Graphing Application will need to be turned off on the TI-83 Plus Family and TI-84 Plus Family. Below are the steps to successfully turn off the Application.
1) Press [APPS] key
2) Select Transfrm from the menu
Next follow the step that matches your calculator:
TI-84 Plus CE and TI-84 Plus C Silver Edtion:
1) Press 2: Quit Transfrm Graphing
TI-84 Plus Silver, TI-84 Plus and TI-83 Plus:
1) Press 1:Uninstall
Please Note: Uninstalling the Application does not erase it from the calculator, it disables it from interfering with the normal graphing modes.
Now the Y= editor should return to the normal display.