MathJax

\[\sqrt{25} = 5\]

\[x ={ {{-b} \pm \sqrt {b^2 - 4 a c} } \over {2 a} }\]

\[\pi=\sum\limits_{n=0}^{+\infty} \frac{{(n!)^2 2^{n+1}}}{(2n+1)!}\]