...or Moodlers can simply use the free and open source Atto plugins that just work - no accounts, no limits, no install/uninstall issues, no misaligned/mis-formatted formulae, etc.
I discovered the catastrophic "rm -rf /" type bug after the Math professor and I had decided that it was unsuitable for his undergrads and we tried to uninstall it.
I've tried Mathslate for Atto and so far, it's pretty good: https://moodle.org/plugins/view/atto_mathslate
and if you need matrices and arrays: https://moodle.org/plugins/view/atto_matrix
All Atto plugins are here: https://moodle.org/plugins/browse.php?list=category&id=53