Lecture 4 - Matrices

What is a Matrix?

• An equation of over 5 numbers or symbols 
• A set of numbers in rows and columns
• A method of finding the n^th value of a series
• A complicated number system

How many rows are in a 7 x 3 matrix?

• 7
• 3
• 21
• 10

How many columns are in a 5 x 4 matrix?

• 5
• 4
• 20
• 9

What are the dimensions of this matrix?

• 2 x 3
• 3 x 2
• 6 x 1
• 1 x 6

What must be true in order to ADD two matrices?

• They must be square.
• The dimensions must be equal.
• The determinant can't equal 0.
• The column of the 1st must equal the row of the 2nd.

Add

• 11    8
  -4     2
• 3     2
  -6    -6
• -3    2
  -4    -6
• 10    8
  -6    2

You can multiply a 2X3 matrix by which matrix?

• 2X2
• 2X12
• 3X12
• 2X3

How many columns are in a 5 x 4 matrix?

• 5
• 4
• 20
• 9

Classify the matrix  

• Square matrix,  Diagonal matrix

• Triangular matrix, Diagonal matrix

• Square matrix, Identity matrix

• Square matrix, triangular matrix

Given matrices A & B: 
A is a (4x33) matrix
B is a (33x1) matrix
 What are the dimensions of the product of A times B?

• 4x1
• 4x33
• 33x1
• Matrix does not exist