Adding, Subtracting, and Multiplying Matrices by Scalars

Add

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

Subtract

• 3    -8
  0   -1
• 3   -4
  8  -13
• -3   8
  0    1
• 3   -8
  -8    1

Dimensions?

• a
• b
• c
• d

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

What would two matrices need to be considered 'equal'?

• The same dimensions and different element values
• The same dimension and the same element values
• Two matrices can never be equal
• two matrices are 'equal' when they are added together to create a matrix of only "0's"

Find B-A

• -3     1
  7     -1
• 1     0
  1     -4
• 4       0
  -6     1
• not possible because rows do not match columns

Find A+B

• 8     10
  8      1 
• 12     25
  7     1
• 10     30
  0     1
• can't add two together because the rows dont match columns

What do w, x, y and z equal in this matrix subtraction?

• w = 13, x = 4, y = 7, z = 23
• w = 13, x = -4, y = 11, z = 23
• w = 13, x = 4, y = 11, z = 23
• w = 13, x = 4, y = 11, z = 17

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 do a, b, c and d equal in this matrix addition?

• a = -1, b = 10, c = 7, d = -11
• a = -1, b = 10, c = -11, d = 7
• a = 10, b = -1, c = 7 , d = -11 
• a = 10, b = -1, c = -11, d = 7