Basic Operation Review

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.

How many rows are in a 7 x 3 matrix?

• 7

• 3

• 21

• 10

Find the product of the two matrices.

• undefined

• -3   16
  17   12
  8   -10

• 3   12 
  -15  -8
  -1   -3

These matrices are being multiplied. Determine the dimension/size of the new matrix. 

• Can't multiply them

• 4  x  2

• 3  x  3

• 4  x  3

In Matrix R (pictured) what element is r₂₃ ?

• 8

• 9.01

• 6

• 1

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  

Find the product of the two matrices.

• 1   2
  6   -8

• -3   -5
  -5   -11

• -2     8
  -6   -12

• 2  -3
  5   -2

find: B*A

• 47     30
  9     5

• 17     15
  42     35

• 10     25
  7     1

• not possible because rows do not match columns

What are the dimensions of this matrix?

• 3x1

• 1x3

• 3x3

• 1x1

Add

• 11    8
  -4     2

• 3     2
  -6    -6

• -3    2
  -4    -6

• 10    8
  -6    2