1.8 Matrices

And a… That’s Row x Column

Example: Find the dimensions.

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

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 =

Addition and Subtraction of Matrices

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!

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

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

ADDITIVE INVERSE OF A MATRIX:

PRACTICE PROBLEMS: 2.) T + U – S =

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

Examples:

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

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

Scalar Multiplication:

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

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