A latex example:

<latex> The characteristic polynomial $f(\lambda)$ of the $3 \times 3$ matrix \[ \left( \begin{array}{ccc} a & b & c
d & e & f
g & h & i \end{array} \right)\] is given by the equation \[ f(\lambda) = \left| \begin{array}{ccc} \lambda - a & -b & -c
-d & \lambda - e & -f
-g & -h & \lambda - i \end{array} \right|.\] </latex>

<latex>

  (3x - 3y + 2z = 11)+(-1(3x +  y  - 3z = 11))=> -4y + 5z = 0

</latex>

another example

<latex>

  \frac{3}{4 \pi}   \sqrt{4 \cdot x^2   12}\\
  \lim_{n \to \infty}
  \sum_{k=1}^n \frac{1}{k^2} = \frac{\pi^2}{6}\\
  \it{f}(x) = \frac{1}{\sqrt{x} x^2}\\
  e^{i \pi} + 1 = 0\;

</latex>

Some more latex:

<latex> $ \begin{align*} \int x^2 dx & = \frac{1}{3}x^3
\therefore\quad\int_0^1 x^2 dx &= \frac{1}{3} \end{align*} $ </latex>

And some more:

<latex> \begin{tabular}{|l|l|p{9cm}|} \hline option & variants & explanation
\hline id & unique string & Identifies the user uniquely.
\hline logmask & ALL & Log everything
\cline{2-3} & DBG & Log only debug
\cline{2-3} & WARN & Log only warning messages
\hline printTID & flag & Print Thread ID or not.
\hline prefix & any string & With this will be prefixed all messages of this user.
\hline p & p & p
\hline p & p & p
\hline p & p & p
\hline p & p & p
\hline \end{tabular} </latex>