Your method is correct, but your denominator is slightly incorrect.
(Sigh) I can't find the link. Somewhere in here is a quick set of instructions. Briefly, if you want to see how the text is coded, left-click on the expression and a box will come up.Originally Posted by Chester
The basics are that all code for LaTeX on this forum is in between the two sets of boxes " [ math ] " and " [ /math ] ." (Without the spaces and quotes!) A decent reference for basic forms can be found here: http://meta.wikimedia.org/wiki/Help:Formula
So far, everything I've found on this page works in this forum.
You get used to it after a while.