1. Objectives Multiply two matrices.
4.2 Matrix Multiplication
Objectives
Multiply two matrices.
Use matrix multiplication to solve mathematical and real-world problems.

2. Glossary Terms dimensions of a matrix matrix multiplication

3. Rules and Properties Matrix Multiplication
If matrix A has dimensions m  n,
and matrix B has dimensions n  r,
then A  B has dimensions m  r.

4. Rules and Properties Matrix Multiplication
To find the entry in row i and column j of AB:
Find the sum of the products of the corresponding entries in row i of A and
column j of B.

5. Key Skills Multiply matrices.
4.2 Matrix Multiplication
Key Skills
Multiply matrices.
Two matrices can be multiplied if their inner dimensions are the same.
2  3
3  1
2  1 2 –3 –1 1 4 8 -1
2(–1) + (–3)2 + (–1)0
1(–1) + 4(2) + 8(0) = –8 7 =
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