<html> <meta charset="utf-8"/> <head> <title>music</title> <script src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS_HTML"></script> </head> <body> \[ \sum_{n=1}^\infty f(x) =6 \tag{1} \] \[ \sum_{n=1}^\infty g(x) \tag{2} \] </body> </html>