(Chapter.exercise) 8.1, 8.2, 8.5, 8.7, 8.12 9.1, 9.4, 9.5, 9.8, 9.11
8.1, 8.2, 8.5, 8.7, 8.12 9.1, 9.4, 9.5, 9.8, 9.11