MATRICES

1

MATRICES

LESSON 31
2
What is a Matrices?

• A matrix is a rectangular array of data entries
  (elements) displayed in rows and columns and
  enclosed in brackets.
• The number of rows and columns in the matrix
  determines its dimensions.

3

• The number of rows is always reported before the
  number of columns.
• Rows go across
• Columns go up and down
• Example

This is a 3 x 2 matrix Because you have 3 rows
and 2 columns
2 4 6 9 5 3
4
Name These Matrices!

• -4 12 6
• 12 3 8 4
• 3 4 8 8

4 5 6 2 3 4

• 4
• 4 6

5
Name These Matrices!

• -4 12 6
• 12 3 8 4
• 3 4 8 8

4 5 6 2 3 4

• 4
• 4 6

3 x 4 matrix
2 x 2 matrix
2 x 3 matrix
6
ADDING MATRICES

• To add 2 or more matrices , we must be sure that
  we have the same frame.
• That is, the same number of rows and columns.
• If you dont have the same dimensions, then the
  question can not be added.

7
ADDING MATRICES

• When adding, you add the 2 numbers that are in
  the exact same position in each matrix.
• These two numbers are called corresponding
  entries

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EXAMPLE

5.3 7.4
8.5 9.1

2 by 1 matrix




(5.3 8.5) (7.4 9.1)
13.8 16.5


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EXAMPLE 2

2 7 3 5 9 4
5 6 4 2 3 2

2 by 3 matrix




(25) (76) (34) (52) (93) (42)
7 13 7 7 12 6


10
YOU TRY

• 3 7 5
• 4 6
• 1 1 1

• 5 6 2
• 4 1
• 1 3 6

__ by __ matrix






11
SOLUTION

3 7 5 2 4 6 1 1 1
5 6 2 6 4 1 1 3 6

3 by 3 matrix




(35) (76) (52) (26) (44) (61) (11) (13)
(16)

• 8 13 7
• 8 7
• 2 4 7

12
SUBTRACTIONThe same rules apply as for addition

5 8 3 6

• 5
• 1 4

-
2 by 2 matrix





(5-2) (8-5) (3-1) (6-4)

• 3
• 2 2

13
SUBTRACTIONThe same rules apply as for addition

8 4 7 9
-2 3 5 -11
-
2 by 2 matrix





(8-(-2)) (4-3) (7-5) (9-(-11))
10 1 2 20

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YOU TRY

5 -7 9 2 4 -6 8 -7 5
2 -3 5 6 -3 7 -5 9 1

-
__ by __ matrix






15
SOLUTION

5 -7 9 2 4 -6 8 -7 5
2 -3 5 6 -3 7 -5 9 1

-
3 by 3 matrix




(5-2) (-7-(-3)) (9-5) (2-6) (4-(-3)) (-6-7) (8-
(-5)) (-7-9) (5-1)
3 -4 4 -4 7 -13 13 -16 4


16
CLASS WORK

• Do Lesson 31 worksheet
• You will find this on the Blog.