# Ampersand conflict when using align inside table

I am trying to use an align environment inside a tabular environment. Whenever I use an & character inside the align environment, there seems to be a conflict, i.e., the following works

\documentclass{article}
\usepackage{amsmath}
\usepackage{array}

\begin{document}
\begin{table}
\begin{tabular}{|m{0.3\textwidth}|m{0.7\textwidth}|}
\hline
\textbf{Compact form} & \textbf{Expanded form} \\
\hline
\begin{equation*}y=\left(x+a\right)^6\end{equation*}
& \begin{align} y =x^6+6x^5a+15x^4a^2+20x^3a^3+15x^2a^4 \nonumber\\ +6xa^5+a^6 \end{align} \\
\hline
\end{tabular}
\end{table}
\end{document}


but the following does not work (note the & characters inside align)

\documentclass{article}
\usepackage{amsmath}
\usepackage{array}

\begin{document}
\begin{table}
\begin{tabular}{|m{0.3\textwidth}|m{0.7\textwidth}|}
\hline
\textbf{Compact form} & \textbf{Expanded form} \\
\hline
\begin{equation*}y=\left(x+a\right)^6\end{equation*}
& \begin{align} y & =x^6+6x^5a+15x^4a^2+20x^3a^3+15x^2a^4 \nonumber\\ & +6xa^5+a^6 \end{align} \\
\hline
\end{tabular}
\end{table}
\end{document}


TeXStudio gives me the following error: ! Forbidden control sequence found while scanning use of \align.

My goal is to obtain something like this

Is there any way to fix this, e.g. by setting an ampersand replacement for align to avoid the conflict?

## 1 Answer

Group the align with braces {...}.

\documentclass{article}
\usepackage{amsmath}
\usepackage{array}

\begin{document}
\begin{table}
\begin{tabular}{|m{0.3\textwidth}|m{0.7\textwidth}|}
\hline
\textbf{Compact form} & \textbf{Expanded form} \\
\hline
\begin{equation*}y=\left(x+a\right)^6\end{equation*}
& {\begin{align} y & =x^6+6x^5a+15x^4a^2+20x^3a^3+15x^2a^4 \nonumber\\
& +6xa^5+a^6 \end{align}} \\
\hline
\end{tabular}
\end{table}
\end{document}