Rather overkill, but you may want to try MediaWiki
Requires: php/mysql
Install time:5 mins not counting download.
For math, there is an incredibly long procedure to set up the partially built-in png math renderer.
Alternatively, you can just install the mathjax extension. Quick process not including downloads.
Also, the LiquidThreads extension makes discussions easier and organized.
I'll post some links later.
This post imported from StackExchange Physics at 2014-04-01 17:40 (UCT), posted by SE-user Manishearth