Math 120 - Finite Mathematics

Calculator Instructions
 TI-83 Row Reduction

This sheet is designed to give you instruction on how to use your calculator to put a matrix, representing a system of linear equations, in row reduced echelon form.

Scenario: Your math teacher asks you to solve the following system of equations.

2x + 3y = 7
3x – 10y = 25

From class, you know you can solve this system by performing row operations on the appropriate matrix. You will use the calculator to do the work.

The 2 X 3 augmented matrix that you will use to represent this system is:

. I will call this matrix A.

1. Enter the matrix in the calculator.

I. Press       to get to the edit matrix menu. Next press . This action selects matrix A to edit.

II. Enter the dimensions of the matrix at the top if the dimensions are incorrect.

III. Enter the six entries from matrix A into the matrix.

2. Use graphing calculator functions to row reduce matrix A.

I. Get back to the home screen. Press     to get to the home screen.

II. Press      to get to the matrix math menu. The option you are looking for is option B: Use  until you see option B, select B and press .

2. Use graphing calculator functions to row reduce matrix A cont.

III. At this point you have “told” the calculator you want to row reduce a matrix. You need to select the matrix you want to row reduce. Since you are working with matrix A, that is the matrix you will select.

(View after step 2 - II)

Press     to get to the matrix name menu. Matrix A is already selected as the default. Next, press .  This action will place the matrix name [ A ] into the rref ( ) operation on the home screen.

Note: You could press  to select other matrices, if you had stored the matrix under a different name.   

IV. Press  . This action will display the row-reduced matrix on the home screen.

Conclusion: Row reduced echelon form shows x = 5 and y = -1 .