Adding, Subtracting and Multiplying Matrices

Find A-B

• -3     1
  7     -1

• 1     0
  1     -4

• -4       0
  6     -1

• not possible because rows do not match columns

Find the product of the two matrices.

• undefined

• -3   16
  17   12
  8   -10

• 3   12 
  -15  -8
  -1   -3

Find the product of the two matrices.

• 1   2
  6   -8

• -3   -5
  -5   -11

• -2     8
  -6   -12

• 2  -3
  5   -2

What do m, n, p and q equal in this scalar matrix multiplication?

• m=8, n=9, p=-4, q=4 

• m=15, n = -45, p=20, q=-5

• m=20, n=-5, p=15, q=-45

• m=-5, n=20, p=-45, q=15

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.

find: B*A

• 47     30
  9     5

• 17     15
  42     35

• 10     25
  7     1

• not possible because rows do not match columns

Algebra High cheerleaders are selling sweatshirts for the Football Team. The inventory of sweatshirts as well as sweatshirts sold on A-Days and B-Days are given in the matrices. Which matrix shows the total of sweatshirts sold in each category, color/size, by the cheerleaders?

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To add or subtract matrices, the ​number of ​ (a)   ​ and ​ (b)   ​ of each matrix must be ​ (c)  

• rows

• columns

• equal.

The matrix N - N is

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The element in row 2 column 1 of matrix ED is:

• -1

• 1

• 2

• 3