Graphing Calculator: Matrices - Part I
A matrix is an array of numbers. These numbers can represent coefficients from a system of equations or a data set. This lesson will show you how to put a matrix into your calculator. To learn more about the algebra of matrices, click here.

If you have a TI-83, you have a MATRIX button on your calculator. If you have a TI-83 Plus or Silver Edition, you will need to access the matrix menu by pressing .

If you have any matrices already in your calculator, you will see a screen similar to the one below. If there are matrices in your calculator, your numbers will probably be different. We won’t worry about any numbers that appear at this point in the lesson.

If your calculator does not have any matrices, you will see the screen below.

The NAMES menu will either show you the dimensions of matrices already stored or that there are no matrices entered. This is also the screen used to place a matrix on your home screen if you are performing calculations (Matrices-Part II).

The MATH menu has a lot of matrix operations that can be performed. For information on those functions, consult your user’s manual.

The EDIT menu is the place to go to input a matrix.

Regardless of whether there are matrices in your calculator, we are now going to put the following matrices into the calculator.

Let’s start with matrix A, which has the notation [A]. Access the matrix menu by using MATRIX or depending on your calculator and go to the EDIT menu, choose , and press . If there is a matrix already in A, we will simply type over the dimensions and the entries. If there is not a matrix in A, you will see the screen below.

The top line of this screen is where you will enter the dimensions of [A], which is a 2 x 2. Simply type 2 , 2 on this top line. You will see the bottom part of the screen change as you make entries.

Now we will enter the four numbers into the calculator. Entries are input beginning with the first row, first column and proceeds across the first row until all entries are in the row. You can simply press after each number and the calculator will automatically move you to the next position in the matrix. After inputting all four numbers for [A], your calculator screen should look like the one below.

To input matrix B, noted as [B], we need to get back to the MATRIX menu and choose the EDIT menu. Once in the EDIT menu, select matrix B and press . As with [A], we need to enter the dimensions of [B] which is also a 2 x 2 matrix.

Follow the same procedure for entering as a 3 x 2 matrix.

When you are finished entering your matrices, you must exit the MATRIX menu by pressing to quit.

You are now ready to add, subtract, and multiply matrices as well as find an inverse of a square matrix. Click here to perform operations on matrices: Matrices-Part II.

S Taylor

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