Chapter 10: Matrices 145
Defining a Matrix
What Is a Matrix?
A matrix is a two-dimensional array. You can display, define, or edit a matrix in the matrix editor.
You can also define a matrix using the MTRX shortcut menu (t `).The TI-84 Plus has 10
matrix variables,
[A] through [J]. You can define a matrix directly in an expression. A matrix,
depending on available memory, may have up to 99 rows or columns. You can store only real
numbers in TI-84 Plus matrices. Fractions are stored as real numbers and can be used in
matrices.
Selecting a Matrix
Before you can define or display a matrix in the editor, you first must select the matrix name. To do
so, follow these steps.
1. Press y | to display the MATRX EDIT menu. The dimensions of any previously
defined matrices are displayed.
2. Select the matrix you want to define. The MATRX EDIT screen is displayed.
4. Press 2 Í 3 Í 3 Í to complete the first
row for X + 2Y + 3Z = 3.
5. Press
2 Í 3 Í 4 Í 3 Í to enter the
second row for 2X + 3Y + 4Z = 3.
6. Press y 5 to return to the home screen. If
necessary, press ‘ to clear the home screen.
Press y ~ to display the
MATRX MATH
menu. Press } to wrap to the end of the menu.
Select
B:rref( to copy rref( to the home screen.
7. Press y
1 to select 1: [A] from the
MATRX NAMES menu. Press ¤ Í. The
reduced row-echelon form of the matrix is
displayed and stored in
Ans.
1X N 1Z = L3 therefore X = L3 + Z
1Y + 2Z = 3 therefore Y = 3 N 2Z
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