1. 1.8 Matrices

2. And a…
That’s Row x Column

3. Example: Find the dimensions.

4. What's your address? 7 in X X21 0 in U U11 -5 in P P12 B34 = –7 E32 =–2
B42 =
– 5
E21 = –3
B54 = 3
D21 =
Does not exist

5. What's your address? K22 = 2 in C C11 N13 = 1 2 in W W32 L35 = 2
2 in C
C11
N13 = 1
2 in W
W32
L35 = 2
Does not exist
H22 =

6. Addition and Subtraction of Matrices

7. To add matrices, we add the corresponding elements
To add matrices, we add the corresponding elements. They must have the same dimensions.
A + B
N + O =
No can do! Must have the same dimensions!

8. When a zero matrix is added to another matrix of the same dimension, that same matrix is obtained.

9. To subtract matrices, we subtract the corresponding elements
To subtract matrices, we subtract the corresponding elements. The matrices must have the same dimensions.

10. ADDITIVE INVERSE OF A MATRIX:

11. PRACTICE PROBLEMS:
2.) T + U – S =

12. Scalar Multiplication:
We multiply each # inside our matrix by k.

13. Examples:

14. Solving a Matrix Equation
Solve for x and y:
x + 8 = 14 – x
2y – 1 = – 13 – y

15. Solving a Matrix Equation
Solve for x and y:
Solution
Step 1: Simplify

16. Scalar Multiplication:

17. 6x+8=26
6x=18
x=3
10-2y=8
-2y=-2
y=1

18. Homework
Page 41 #1 – 11
Page 42 #1 – 9 FC
FC means (1st column)