Help On LaTeX eqnarray

# eqnarray

     \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.