\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.