add solution to Exercise 7.2-5.

Included are the following 2 files:

	7.2-5.pdf
	7.2-5.tm

Thank you!
							Lawrence X. Amlord
							  Jul 28th, 2014
							  Xi'an, China
add solution to Exercise 7.3-1.

Included are the following 2 files:

	7.3-1.pdf
	7.3-1.tm

Thank you!
							Lawrence X. Amlord
							  Jul 31st, 2014
							  Xi'an, China