\begin{eqnarray}
math formula 1 \\
math formula 2 \\
.
.
.
\end{eqnarray}
The eqnarray environment is used to display a sequence of
equations or inequalities. It is very much like a three-column
array environment, with consecutive rows separated by \\
and consecutive items within a row separated by an &. An
equation number is placed on every line unless that line has a
\nonumber command.