1. SAT Problem of the Day

2. 4.2 Matrix Multiplication 4.2 Matrix Multiplication Objectives: Multiply two matrices Use matrix multiplication to solve mathematical and real-world problems

3. Matrix Multiplication A football team scores 5 touchdowns, 4 extra points, and 2 field goals. A touchdown is worth 6 points, an extra point is worth 1 point, and a field goal is worth 3 points. The final score is: (5 touchdowns)(6 pts) + (4 extra points)(1 pt)+ (2 field goals)(3 pts) = 30 points + 4 points+ 6 points = 40 points touch- downs extra points field goals 542 point values 6 1 3 (5)(6) + (4)(1) + (2)(3) total score

4. Matrix Multiplication To multiply any two matrices, the inner dimensions must be the same. Then the outer dimensions become the dimensions of the resulting matrix. 2 x 33 x 4 inner dimensions outer dimensions product dimensions = 2 x 4

5. SAT Problem of the Day

6. Example 1 Find the product. 1 x 33 x 2 (2)(8) + (5)(0) + (0)(2)(2)(1) + (5)(4) + (0)(5) = 1 x 2

7. Practice Let A =and B = Find AB and BA.

8. Homework Lesson 4.2 exercises 1, 2, 7-15 odd, 16, 19, 20, 24-26, 30.