1. In Exercises 21–30, find the indicated prod ucts (if they exist) of the matrices given in Exercises 1–10. 21. a. AC b. CA 22. a. AE b. EA 23. a. AD b. DA 24. a. GH b. HG 25. a. CG b. GC 26. a. DK...

1. In Exercises 21–30, find the indicated prod ucts (if they exist) of the matrices given in Exercises 1–10.

21. a. AC b. CA

22. a. AE b. EA

23. a. AD b. DA

24. a. GH b. HG

25. a. CG b. GC

26. a. DK b. KD

27. a. JB b. BJ

28. a. HK b. KH

29. a. AF b. FA

30. a. AB b. BA

2. Use matrix multiplication and Figure 11.2 to find the sale price and the regular price of purchasing five CDs and three DVDs.

3. Use matrix multiplication and Figure 11.2 to find the sale price and the regular price of purchasing four CDs and one DVD.