Merge pull request #56 from KellyBlack/black_dev

Changed the formatting for an equation for the second day of undetermined coefficients.
merge
fix conflict
Merge pull request #57 from KellyBlack/black_dev

talk on lf parameters
main file
Merge branch 'yao_dev' of github.com:guangmingyao/ODE-Recitation-Activities into yao_dev
Merge pull request #58 from KellyBlack/black_dev

Updated discussion on forced oscillations.
Merge pull request #59 from KellyBlack/black_dev

Updated the discussion on the introduction to linear algebra.
made changes on monday and wednesday notes about the typos
Merge branch 'yao_dev' of github.com:guangmingyao/ODE-Recitation-Activities into yao_dev
Merge pull request #35 from guangmingyao/yao_dev

Yao dev
Updated the talk on solving linear equations and RREF