Assign Values to Variables in TI83 Plus Equation Solver
After you have entered an equation in the Equation Solver on the TI83 Plus graphing calculator, 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 (as illustrated in the first picture, where values are assigned to variables A and W).
The bound variable at the bottom of the screen, as illustrated in the first picture, is where you enter the bounds of the interval containing the solution you’re seeking. The default setting for this interval is [–10^{99}, 10^{99}], as is indicated by bound = {–1E99, 1E99}. 1E99 is 10^{99} in scientific notation. The ellipsis at the end of the line containing this variable indicate that you have to repeatedly press
to see the rest of the line.
This default setting is more than sufficient for equations that have a unique solution. So if your equation has a unique solution, you don’t have to do anything with the value in the bound variable.
When the equation you’re solving has multiple solutions, it’s sometimes necessary to redefine the bound variable.
To redefine the bound variable:

Use
to place the cursor anywhere in the line containing the bound variable.

Press [CLEAR] to erase the current entry.

Press [2nd][ ( ] to insert the left brace.

Enter the lower bound, press [.], enter the upper bound, and then press [2nd][ ) ] to insert the right brace.

Press [ENTER] to store the new setting in the bound variable.