# TI-84 Plus Calculator's Equation Solver

The TI-84 Plus graphing calculator Equation Solver solves an equation for one variable given the values of the other variables in the equation. The Solver is capable of dealing only with real numbers and is capable of finding only real-number solutions.

The following lists the basic steps for using the Equation Solver. If you have never used the Equation Solver before, the Equation Solver is a bit tricky. After you have had experience using the Solver, you can refer back to this list, if necessary, to refresh your memory on its use.

If necessary, set the Mode for real-number arithmetic.

Because the Equation Solver is equipped to deal only with real numbers, press

**[MODE]**and highlight all entries on the left.Enter a new equation (or edit the existing equation) in the Equation Solver.

Assign values to all variables except the variable you’re solving for.

After you have entered an equation in the Equation Solver, the values assigned to the variables in your equation are the values that are currently stored in those variables in your calculator. You must assign an accurate value to all variables except the variable you’re solving for. These values must be real numbers or arithmetic expressions that simplify to real numbers.

To assign a value to a variable, use

to place the cursor on the number currently assigned to that variable and then key in the new value. As you start to key in the new value, the old value is erased. Press

**[ENTER]**when you’re finished entering the new value.Enter the bounds for the interval that contains the solution.

Enter a guess for the solution.

Guess at a solution by assigning a value to the variable you’re solving for. Any value in the interval defined by the

**bound**variable will do. If your guess is close to the solution, the calculator quickly solves the equation; if it’s not, it may take the calculator a while to solve the equation.If your equation has more than one solution, the calculator will find the one closest to your guess.

If the variable you’re solving for is assigned a value (guess) that isn’t in the interval defined by the

**bound**variable, then you get the ERR: BAD GUESS error message.Press [ALPHA][ENTER] to solve the equation.