如何水平移动子方程环境

Question

我怎样才能将subequations环境移到左边？\hspace*{}没用。

\documentclass[journal]{IEEEtran}

\usepackage{mathtools}
\usepackage[overload]{empheq}

\begin{document}

\title{...}
\author{...}

\maketitle

\begin{abstract}...\end{abstract}

%\hspace*{-2cm} 
\begin{subequations}
    %\hspace*{-2cm}
    \begin{align}[left = \empheqlbrace\,]
    %\hspace*{-2cm}
    &a,\\
    &b,
    \end{align}
\end{subequations}
\end{document}

Answer 1

使用flalign环境：

\documentclass[journal]{IEEEtran}

\usepackage{mathtools}
\usepackage[overload]{empheq}
\usepackage{lipsum}

\begin{document}

\title{...}
\author{...}

\maketitle

\begin{abstract}...\end{abstract}
\lipsum[11]
\begin{subequations}
    %\hspace*{-2cm}
    \begin{flalign}[left = \empheqlbrace\,]
    a & = c + d, & \\
     b & = e + f,
    \end{flalign}
\end{subequations}
\lipsum

\end{document} 

Answer 2

您可以将其放置在\parbox任意宽的命令内（但至少要满足方程式的需要）

\documentclass{article}

\usepackage{mathtools}
\usepackage[overload]{empheq}

\begin{document}

\title{...}
\author{...}

\maketitle

\begin{abstract}...\end{abstract}

Test text here:

\parbox{0.14\textwidth}{\begin{subequations}
    %\hspace*{-2cm}
    \begin{align}[left = \empheqlbrace\,]
    %\hspace*{-2cm}
    &a,\\
    &b,
    \end{align}
\end{subequations}}
\end{document}

输出：