(Copied from https://www.dokuwiki.org/plugin:mathjax)
NOTE that the default configuration uses \$ (dollar signs) to delimit TeX formulas. This may cause trouble if you have \$ characters in any pages. The default configuration also lets you escape the dollar signs, however, by changing them to \$. This should correct any problems you might have.
Once the plugin is installed, you can write TeX formulas in your wiki with the following syntax (by default — all delimiters are configurable):
Use dollar signs:
$a^2 + b^2 = c^2$
$a^2 + b^2 = c^2$
or escaped parentheses:
\(1+2+\dots+n=\frac{n(n+1)}{2}\)
\(1+2+\dots+n=\frac{n(n+1)}{2}\)
To display math on its own line, use double dollar signs:
$$ \frac{d}{dx}\left( \int_{0}^{x} f(u)\,du\right)=f(x) $$
$$ \frac{d}{dx}\left( \int_{0}^{x} f(u)\,du\right)=f(x) $$
or escaped square brackets:
\[ \sin A \cos B = \frac{1}{2}\left[ \sin(A-B)+\sin(A+B) \right] \]
\[ \sin A \cos B = \frac{1}{2}\left[ \sin(A-B)+\sin(A+B) \right] \]
A wide range of math environments will work as well:
$\begin{align*}
e^x & = 1 + x + \frac{x^2}{2} + \frac{x^3}{6} + \cdots \\
& = \sum_{n\geq 0} \frac{x^n}{n!}
\end{align*}$
$\begin{align*} e^x & = 1 + x + \frac{x^2}{2} + \frac{x^3}{6} + \cdots \\ & = \sum_{n\geq 0} \frac{x^n}{n!} \end{align*}$