I want to left-align the following equation. I don't want that to be centred

Question

\documentclass[10pt]{article}
\usepackage{amsmath}
\begin{document} 
\begin{equation*}
\epsilon(\lambda_1,...,\lambda_n)=sgn\prod_{\substack{r=s}}(\lambda_s-\lambda_r). 
\end{equation*}
\end{document}

Answer 1

Either you use the fleqn option in your document class, but then all equations will be left-aligned, or you have to use the flalign* environment:

\documentclass[10pt]{article}

\usepackage[showframe, nomarginpar]{geometry}

\usepackage{amsmath}

\DeclareMathOperator{\sgn}{sgn}

\begin{document}

\begin{flalign*}
 & \epsilon(\lambda_1,...,\lambda_n)=\sgn\prod_{r < s}(\lambda_s-\lambda_r). &
\end{flalign*}

\end{document}