Matrix Review

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

In Matrix R (pictured) what is the value of element R_3,2

• 8
• 9.01
• 6
• 1

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

Multiply

• 1   2
  6   -8
• -3   -5
  -5   -11
• -2     8
  -6   -12
• 2  -3
  5   -2

Multiply

• 20     15    -10
  30     -5         0
• -20      15     -10
  30     -5          0
• 1        8       3
  11     4        5
• 20     -15     10
  -30         5        0  

If the matrices can be multiplied, what dimension is the product? If not, write undefined.

• undefined

• ( 3 x 1 )

• ( 1 x 2 )

• ( 3 x 2 )

Which of the following must be true for a matrix to be invertible? Choose all that apply.

• The matrix must be square.

• The determinant must be zero.

• The determinant must not be zero.

• The matrix cannot have any negative entries.