Homework:
13, 18, 25, and 26 from section 2.6
https://ocw.mit.edu/courses/mathematics/18-06-linear-algebra-spring-2010/assignments/MIT18_06S10_pset2_s10_soln.pdf
13, 36, and 40 from section 2.7
Lec 5 | MIT 18.06 Linear Algebra, Spring 2005
Lec 3 | MIT 18.06 Linear Algebra, Spring 2005