Notes

Matrices are named with capital letters.

Each number in a matrix is an element of that matrix. In matrix A, a11 = the element in row 1, column 1 a21 = the element in row 2, column 1 a12 = the element in row 1, column 2 a22 = the element in row 2, column 2

The dimension of a matrix are written as #x#. # rows x # columns Matrix A is a 2x2 (read “2 by 2”)

A square matrix means the number of rows equals the number of columns. Matrix A is a square matrix because it is a 2x2. Other square matrices are 3x3, 4x4, 5x5, and so on.

***2x4 is NOT a square matrix

A matrix is just an array of numbers. Matrices is the plural form of matrix

2221

1211

aa

aaA

85

02B

Example:

a)What is the element in b21 ?

b)What is the location of 0?

-5

b12

333231

232221

131211

aaa

aaa

aaa

A This is a 3x3 matrix.

192

13264

368

C

In matrix C,

a)What is the element in c23

b)What is the element in c32

c)What is the location of 1

d)What is the location of -3

b33

b13

-9

13

Try these:

What are the dimensions of the following matrices?

9

5

1

X 803 Y

13764

30025

0239

W

125

1926

1411

T

3x1 1x3 3x4 3x2