MathTest

A much more detailed version of this is here: http://meta.wikimedia.org/wiki/Help:Displaying_a_formula

A single equation:
\operatorname{erfc}(x) = \frac{2}{\sqrt{\pi}} \int_x^{\infty} e^{-t^2}\,dt = \frac{e^{-x^2}}{x\sqrt{\pi}}\sum_{n=0}^\infty (-1)^n \frac{(2n)!}{n!(2x)^{2n}}	$ \operatorname{erfc}(x) = \frac{2}{\sqrt{\pi}} \int_x^{\infty} e^{-t^2}\,dt = \frac{e^{-x^2}}{x\sqrt{\pi}}\sum_{n=0}^\infty (-1)^n \frac{(2n)!}{n!(2x)^{2n}} $
Multiple-line equation (default alignments):
\begin{align} y &=& x + 2 \\ 5x + 7z &=& 8y^2 + 2y - 5 \end{align}	$ \begin{align} y &=& x + 2 \\ 5x + 7z &=& 8y^2 + 2y - 5 \end{align} $
Multiple-line equation (user-set alignments, Right-Center-Left):
\begin{array}{rcl} y & = & x + 2 \\ 5x + 7z &=& 8y^2 + 2y - 5 \end{array}	$ \begin{array}{rcl} y & = & x + 2 \\ 5x + 7z &=& 8y^2 + 2y - 5 \end{array} $