1. Show that eq.(6-39) in page 181 leads to eq.(6-40). 

2. Solve Example 6-11. 

3. Solve Example 6-14. 

4. Solve Example 6-15. 

5. Solve Example 6-16. 

6. Solve Example 6-18. 

7. Solve Example 6-20. 

8. Solve Example 6-22. 

9. Solve Example 6-25. 

10. Solve Example 6-36. 

11. Solve Example 6-49. 

12. Solve Example 6-50.