There are three environments that put LaTeX in math mode:
math
displaymath
equation
The math
environment can be used in both paragraph and LR mode,
but the displaymath
and equation
environments can be used
only in paragraph mode. The math
and displaymath
environments are used so often that they have the following short forms:
\(...\) instead of \begin{math}...\end{math} \[...\] instead of \begin{displaymath}...\end{displaymath}
In fact, the math
environment is so common that it has an even
shorter form:
$ ... $ instead of \(...\)