Enter or Edit Equations in TI83 Plus Equation Solver
The first step in using the Equation Solver on the TI83 Plus graphing calculator is to set the Mode for realnumber arithmetic. Because the Equation Solver is equipped to deal only with real numbers, press [MODE] and highlight all entries on the left.
To enter a new equation in the Equation Solver, follow these steps:

Press [MATH][0] to access the Equation Solver from the Math menu.
When the Equation Solver appears, it looks like one of the pictures shown here. The first picture shows the Equation Solver when no equation is stored in the Solver; the second picture depicts the Solver and the equation currently stored in it.

If your Equation Solver already contains an equation, repeatedly press
until the screen titled EQUATION SOLVER appears.

If you need to, press [CLEAR] to erase any equation in the Solver.

Enter the equation you want to solve.
The equation you enter must be set equal to zero and can contain only real numbers. For example, if you want to solve the area equation A = L*W, enter it as 0 = A – L*W or as 0 = L*W – A.
You can also use a function that you’ve entered in the Y= editor in the definition of your equation. For example, if Y_{1} = X – 1 in the Y= editor, you can enter 1/Y_{1} – 1 in the Equation Solver to solve the equation 1/(x – 1) – 1 = 0.
To insert such a function into the equation, press
to access the Function menu, and then press the number of the function you want to enter.

Press [ENTER]to enter the equation in the solver.
To edit an equation that is already entered in the Equation Solver, follow these steps:

Follow the above Steps 1 and 2.

Edit the equation and press [ENTER] when you’re finished.