Testing LaTeX with MathJax

$3_{5}$ $$42^{25}$$
extensions: ["tex2jax.js"], jax: ["input/TeX", "output/HTML-CSS"],
Does not work

But this:

<script src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML" type="text/javascript"></script>

<script type='math/tex; mode=display'>   \{ 0, 1, 2 \} </script>

Results in something pretty: $$\{ 0, 1, 2 \} \mathcal{L}$$