Small
Greek letters
are created like this: \alpha, \beta, \gamma...
if you want to use capitals you have to put it like this:
{\rm A}, {\rm B},
\Gamma, \Delta...
$\lambda, \xi, \pi, \mu, \Phi, \Omega $
There's a great deal of mathematical symbols:
like 
or 
or 
...
Exponents and indices can be put high or low with help of
^ and _
$a_{1}$ \qquad
$x^{2}$ \qquad
$e^{-\alpha t}$ \qquad
$a^{3}_{ij}$
Squareroots are created like this: \sqrt ,
n/-th squareroot with \sqrt[n/].
The size of the squareroot is processed by LaTeXautomatically.
$\sqrt{x}$ \qquad
$\sqrt{ x^{2}+\sqrt{y} }$
\qquad $\sqrt[3]{2}$