1. Operations with Matrices: Multiplication
TSWBAT perform scalar multiplication; multiply to matrices

2. Scalar Multiplication
Multiplying a matrix by a real number
Multiply each element by the real number
Just like distributing
-1 4
3 7
0 -8 5 -5 20 15 35
-40

3. Examples
3 -4
1 6
-4 5 7
4 5
-1 3
-2 8 -2
4 7
-3 5 2 +
0 -2
6 4

4. Class work
WB pg 23
1-6
Turn in when finished
Homework
Worksheet

5. Multiplying Two Matrices
You can only multiply matrices if the columns of the first matrix have the same number of elements as the rows of the second matrix
-1 2
4 0
7 -5 3
1 6 8
2 x 2
2 x 3
2 x 3

6. Multiplying Two Matrices
Multiply the elements of each row of the first matrix by the corresponding elements in each column of the second matrix
Find the sum of each set of products
-1 2
4 0
7 -5 3
1 6 8
-1(7) +
2(1)
The answer goes in the corresponding spot, Row 1 Column 1

7. Example -1 2 4 0 7 -5 3 1 6 8 -1(7) + 2(1) -1(-5) + 2(6) -1(3) + 2(8)
-1 2
4 0
7 -5 3
1 6 8
-1(7) + 2(1)
-1(-5) + 2(6)
-1(3) + 2(8)
4(7) + 0(1)
4(-5) + 0(6)
4(3) + 0(8)

8. Examples
3 -2
1 0
0 -5
6 8
0 -2
5 1
-3 6
4 3 1
7 1 2
-3 5 8
6 4
-2 -8

9. Using your Calculator Push the green ALPHA button Push the zoom button
Choose the dimensions of the matrix, click OK
Enter the numbers
Choose the operations and repeat to enter the second matrix
If it says error, the 2 matrices cannot be multiplied

10. Class work
WB page 24
14-18
Homework
Worksheet