Aligned equations in LaTeX

Several equations aligned at the = sign are written with the align environment. The & character marks the alignment point and \\ ends a row. align numbers every equation, align* numbers none.

\begin{aligned} (a+b)^2 &= (a+b)(a+b) \\ &= a^2 + 2ab + b^2 \end{aligned}

\begin{align}
  F &= ma \label{eq:newton} \\
  E &= mc^2 \nonumber
\end{align}

Common mistakes

• Nesting align inside $$...$$: align is already display math and fails inside $$.
• The old eqnarray environment: it leaves too much space around the equals sign.

See also

• System of equations in LaTeX
• Cross-references in LaTeX
• Equation numbering in LaTeX