Wetzel

Math 110

7.2(10.2) – The Algebra of Matrices

Adding and Subtracting Matrices –

• The matrices must be the same size!
• Add or Subtract the corresponding elements.

Ex.

1.)  A + D                    2.)  D - A                     3.)  B + C

Zero Matrix, O

• A matrix whose elements are all zero.

Scalar Multiplication –

• Multiplying a matrix by a real number.
• Multiply each element in the matrix by the real number.

Ex.

4.)  -2B                                    5.)  5C

Multiplication of Matrices –

• Multiplying two matrices together, the number of columns in the first matrix must be equal to the number of rows in the second matrix.

A         X         B

                                 n x m       X        m x o    

Ex.:

6.)  AD                        7.)  DA            8.)  BC             9.)  CB

HW:   6^th & 5^th Ed.  #1-23odd