1. Lesson 43: Working with Matrices: Multiplication
Texas Algebra I
Lesson 43: Working with Matrices: Multiplication

2. Lesson Objectives The student will be able to:
Multiply a given matrix:
By a scalar (constant)
By another matrix

3. What is A Matrix?
A matrix is a rectangular arrangement of numbers in rows and columns.
Row
column
This matrix has 2 rows and 3 columns, so it is said to be a 2 x 3 matrix.

4. Multiplying Matrices: by a scalar
A scalar is a constant term that is being multiplies by a matrix. Ex: In this example, 5 is the scalar.

5. Multiplying Matrices: by a scalar
To find the product, multiply each element by the scalar. Ex:

6. Multiplying Matrices: by another matrix
Ex: First, multiply the first row by the first column: This is your first element of the solution:

7. Now, multiply the first row by the second column: This will be the next element. Proceed on and do 2nd row by first column and 2nd row by 2nd column:

8. The Product!!
Whew!! After all that, here’s the answer:

9. Lesson Objectives The student will be able to:
Multiply a given matrix:
By a scalar (constant)
By another matrix