eopl Essentials of Programming Languages, third edition It is an amazing book. I take notes and do exercises in this book. Here is the record. <script type="text/javascript" src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=default"></script> $$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$$ \(x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\)