Q:   I am trying to focus what I should study. hould we be prepared to answer questions on Gauss-Jordan Elimination, Residuals, or Cholesky factorization. I recall us going over those topics briefly but not to the same extent as some other topics like LU factorization and Machine Epsilon.
A:   as mentioned in class: no Gauss-Jordan, Cholesky is just LU for symmetric matrices A = A'. Your emphasis on LU and epsilon is correct.