MathJax is a javascript LaTeX renderer for mathematical formulae.
Therefore it to work you need to have javascript enabled in your browser (it is enabled by the default). If the page contains a lot of mathematical formulae and/or you are on the slow connection, it takes several seconds for MathJax to load and to be executed (before this happens you see the raw code and in the bottom left corner of your browser there is a percentage shown). Do not interrupt execution by clicking on the window.
No extra installation required!
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