Mathjax standard delimiters are
\( .... \) , \[ ...\] and $$...$$
$..$ is not define as delimiters.
http://docs.mathjax.org/en/latest/tex.html#tex-and-latex-math-delimiters
Mathjax standard delimiters are
\( .... \) , \[ ...\] and $$...$$
http://docs.mathjax.org/en/latest/tex.html#tex-and-latex-math-delimiters