How to add two 3 x 3 matrices on a GDC (graphical display calculator). This explanation uses the TI-82/83/84 range of calculators.

The calculator has memory slots set aside for matrices: [A], [B], ..., [J].

1. Press the MATRIX key. This brings you to a menu with a list of all the matrices.

2. Use the right-arrow twice to move over to EDIT so that you can create a matrix.

3. Type a 1 (or ENTER) for matrix [A].

4. Press 3 ENTER 3 ENTER to indicate a 3x3 matrix.

5. Now choose values of the elements of the matrix until you've filled the matrix.

6. Return to the main screen by pressing 2ND MODE.

7. Repeat the last 4 steps to create matrix B.

8. Press MATRIX then ENTER

9. Press the + button

10. Press MATRIX then 2 then ENTER

A display of the sum A + B will be shown. Use the cursor keys to move about the matrix to see all the entries.

The calculator has memory slots set aside for matrices: [A], [B], ..., [J].

1. Press the MATRIX key. This brings you to a menu with a list of all the matrices.

2. Use the right-arrow twice to move over to EDIT so that you can create a matrix.

3. Type a 1 (or ENTER) for matrix [A].

4. Press 3 ENTER 3 ENTER to indicate a 3x3 matrix.

5. Now choose values of the elements of the matrix until you've filled the matrix.

6. Return to the main screen by pressing 2ND MODE.

7. Repeat the last 4 steps to create matrix B.

8. Press MATRIX then ENTER

9. Press the + button

10. Press MATRIX then 2 then ENTER

A display of the sum A + B will be shown. Use the cursor keys to move about the matrix to see all the entries.

## Software/Applets used on this page

## Glossary

### gdc

graphic display calculator

### matrix

a rectangular or square grid of numbers.

### range

In Statistics: the difference between the largest and smallest values in a data set; a simple measure of spread or variation

In Pure Maths: the values that y can take given an equation y=f(x) and a domain for x.

In Pure Maths: the values that y can take given an equation y=f(x) and a domain for x.