1. What does this say? Matrix Multiplication 5 14 5 13 25 9 19 3 12 15 19 5. 16 18 5 16 1 18 5! What does this say? 33 47 31 44 79 106 47 66 33 33 42 57 29 34 82 109 52 70 37 53 37 55 63 92

2. Product of matrices The entry in the i th row and j th column of this new matrix is a result of the sum of the product of entries in row i of the first matrix and column j of the second matrix: Essentially, each row of the first matrix is paired with each column in the second matrix. If one matrix has m rows and p columns and a second matrix has p rows and n columns, then the matrix resulting from their product will be of order

3. More examples

4. More, more examples

5. Application 1 McDonald’s has sales of its Big Mac, McFish and McChicken sandwiches in Hawaii and Alaska. Matrix X stores info about how many were sold and matrix Y keeps the sales price per item. What is XY and what does it mean?

6. Application 2 Encode the phrase “now or never” with the given code matrix: 14 15 23 27 15 18 27 14 5 22 5 18 n o w o r n e v e r