Merge pull request #33 from guangmingyao/yao_dev

Yao dev
Merge pull request #34 from guangmingyao/yao_dev

Yao dev
Set the clicker quizzes to print.
Updated the second day on method of undetermined coefficients.
Merge pull request #56 from KellyBlack/black_dev

Changed the formatting for an equation for the second day of undetermined coefficients.