>>23
This is how it's done:

\eqn{\sum _{n=0}^{\infty}{\frac{f^{(n)}(a)}{n!}}(x-a)^{n}}

You can also insert pgfplots into your posts using \icode{\addplot}. For example, the following is \eqn{e^{\sin{x}}}

\addplot[domain=-5:5,samples=100,color=red]{exp(sin(deg(x)))}

You can click on the </> button which is located next to post numbers in order to view post the source code and try certain parts yourself.