These are questions that students in classes that use the TI-86 often ask. If you are having a particular difficulty, it is likely the answer to your question is in the list below. Links to particular sections are included to help you find the answer you need.
When a graph doesn't "look right" it is most likely because you have either entered the function incorrectly or you have not set the window properly.
There are two main reasons that a graph may not show up.
a) The function may be turned off. Make sure that the equal sign is dark. If not, then move the cursor to the equal sign and press enter to turn the function on.
b) Your window may not be set correctly.
The axes can be turned on and off with the FORMAT menu.
This message is shown when you have a statistical plot turned on and there are no values in lists to graph or they are not evenly matched. You need to turn the plot off.
The FORMAT setting will determine whether rectangular or polar coordinates are shown.
The MODE setting will determine the type of graph that can be drawn.
The TABLE must be set to ASK before you can enter the values you want.
You can solve an equation if you can enter both sides of the equation into the graph editor and use intersect to find the solution.
You can store the answer in the variable X and then enter the expression to check your answer.
You can use the storage area ENTRY to recall several recent entries.
There is a good chance that your expression has not been entered with the proper placement of parentheses. You must enter parentheses to maintain the proper order of operations.
Use the cursor and the key to lighten or darken a screen.
The CATALOG menu has every function, variable, list, etc. in the catalog. You may want to enter frequently used functions in the CUSTOM menu.