Exer. 7.1
Exer. 7.1, another answer
Exer. 7.1, yet another answer
Exer. 7.2
Exer. 7.3
Exer. 7.3, another answer
Exer. 7.4
Exer. 7.5
Exer. 7.6
Exer. 7.7
Exer. 7.8