Homework:
13, 36, and 40 from section 2.7
https://ocw.mit.edu/courses/mathematics/18-06-linear-algebra-spring-2010/assignments/MIT18_06S10_pset2_s10_soln.pdf
18, 23, 30, and 32 from section 3.1
Lec 6 | MIT 18.06 Linear Algebra, Spring 2005
Lec 4 Factorization into A = LU