Ah, good to know. I was just trying to make things work with the (slightly) different versions of markdown and mathjax. So in that case, the gitbook version is mostly correct except you'll want to replace the few instances of `$$ $$` with `\[ \]`. I've already stripped out the other extra backslashes that this forum required. I'll convert the gitbook markdown files to use that convention instead of `$$` tonight.