1. Introduction to Matrices
AQR

2. A matrix is an array of numbers.
The rows are the grades of each student.
The columns are the designated assignments
The dimensions of a matrix are
# of rows by # of columns

3. So a “10×20” matrix means 10 rows and 20 columns
So a “10×20” matrix means 10 rows and 20 columns. What are the dimensions of Dr. Snape’s grade book matrix?

4. Adding & Subtracting Matrices
To add or subtract matrices both matrices must have the same dimensions.

5. Scalar Multiplication
When you multiply a matrix by a number.