Section 2.4 – Matrices
1
Section 2.4
Matrices
A
matrix
is an ordered rectangular array of numbers.
A matrix with
m
rows and
n
columns has
size
or
dimension
m
x
n
.
The entry in the
i
th row and
j
th column is denoted
by
ij
a
.
The real numbers that make up the matrix are called
entries
or
elements
of the
matrix.
Example 1:
Given
⎟
⎟
⎟
⎟
⎟
⎠
⎞
⎜
⎜
⎜
⎜
⎜
⎝
⎛
−
−
−
−
=
11
3
1
20
10
0
9
3
5
7
7
2
A
,
a.
what is the dimension of
A
?
b.
identify
33
a
.
A matrix with only one column or one row is called a
column matrix
(or
column
vector
) or
row matrix
(or
row vector
), respectively.
A
square matrix
is a matrix having the same number of rows as columns.
Example:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
1
4
9
3
Addition and Subtraction of Matrices
If A and B are two matrices of the same dimension,
1.
The sum A + B is the matrix obtained by adding the corresponding entries in the two
matrices.
2.
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 Fall '10
 AbdelnourAhmedZaid
 Math, Linear Algebra, Real Numbers, Addition, Multiplication, Matrices

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