add solution to Exercise 6.2-2.

Included are the following 2 files:

	6.2-2.pdf
	6.2-2.tm

Thank you!
							Lawrence X. Amlord
							  Jun 14th, 2014
							  Xi'an, China
add solution to Exercise 6.2-3.

Included are the following 2 files:

	6.2-3.pdf
	6.2-3.tm

Thank you!
							Lawrence X. Amlord
							  Jun 14th, 2014
							  Xi'an, China