Calculators

The TI-83+ is the calculator that's commony used by most students in this course. 

To learn how to use your calculator, you may click here.


One of the more valuable features of the calculator is the "equation solver", described below.

Equation Solver:

The example below illustrates how the equation solver is used.

Note: the variable "x" is embedded in equations by pressing the [X,T,θ,n]"key.
 Exponents are achieved using the "^" key.

Example: Solve 3x²e^-x - 2x = 4

1.  MATH

2.  0: Solver...

3.  Scroll Up Using Arrow Key

4.  CLEAR. Your calculator screen should display the following:

       
       EQUATION SOLVER

       eqn: 0 =

Rewrite your equation so that everything is on one side of the equal sign; this is the so-called "zero equal" form. The "zero" side of the equation is waitin for you. You type in the right side of the equation.

5.  eqn: 0 = 3x^2 e^(-x) - 2x - 4

6.  ENTER

7.  X = (some number).  The cursor will be flashing on this number, but the number is not your solution. The number displayed is whatever the solution was the last time the solver was used, or whatever was the last value of x stored in memory. Ignore this number.  Also ignore the information displayed on the bound" line that is below the "X = " line.

8. With the flashing cursor stil on top of the current value of x, enter a "guess" value for the solution. The closer your guess is to the correct value of x, the shorter will be the wait time for the actual solution to appear, but this wait time is seldom more than five seconds, and is usually just one or two seconds, so little time should be spent trying to make a good guess, so just pick a number--any number, and enter it in place of whatever number is already displayed for x. I always pick the same number: 5.

Before proceeding to the next step, make sure the flashing cursor is on the x= line.


9. ALPHA ENTER (SOLVE). Press the ALPHA key, and then the ENTER key.  After a second or two, the solution is displayed in place of the guessed number, and you're done--maybe.  If there is more than one solution to the equation, you will need to enter a second guess.  I usually start with the guesses, - 5, or  0. With a different guess, you might get the same solution as before, so you will need to keep guessing if you know there is another solution, until the other solution is found.  You might wish to practice this procedure by finding the three solutions to the following equation: x³ + 5x² - x -11 = 0.