我怎样才能将以下内容整体左对齐？

Question

    \documentclass[11pt,a4paper]{article}
    \usepackage{blindtext}
    \usepackage{mathtools}
    \usepackage{IEEEtrantools}

\begin{document}
\begin{IEEEeqnarray*}{rCl}
E&=&(ab)^{m}.\,\text{(Hypothesis).}
\\
&=&(ab)\times (ab)\times (ab)\times \dotsm m\,\text{factors}.\,\text{(Definition of an index).}
\\
&=&(a\times a\times a\times \dotsm m\,\text{factors}\times \\
&&(b\times b\times b\times \dotsm m\,\text{factors}.\,\text{(Laws of association and commutation).}
\\
E&=&a^{m}\times b^{m}.\,\text{(Definition of an index).}
\end{IEEEeqnarray*}
\end{document}

Answer 1

我将使用 AMS 对齐，因为无论如何您都要加载包：

   \documentclass[11pt,a4paper,fleqn]{article}
    \usepackage{blindtext}
    \usepackage{mathtools}

\setlength\mathindent{0pt}
\begin{document}
\noindent X\dotfill X
\begin{align*}
E&=(ab)^{m}.\,\text{(Hypothesis).}
\\
&=(ab)\times (ab)\times (ab)\times \dotsm m\,\text{factors}.\,\text{(Definition of an index).}
\\
&=(a\times a\times a\times \dotsm m\,\text{factors}\times \\
&(b\times b\times b\times \dotsm m\,\text{factors}.\,\text{(Laws of association and commutation).}
\\
E&=a^{m}\times b^{m}.\,\text{(Definition of an index).}
\end{align*}
\end{document}

也许

  \documentclass[11pt,a4paper,fleqn]{article}
    \usepackage{blindtext}
    \usepackage{mathtools}

\setlength\mathindent{0pt}
\begin{document}
\noindent X\dotfill X
\begin{align*}
E&=(ab)^{m}\tag{Hypothesis}
\\[\jot]
&=\underbrace{(ab)\times (ab)\times (ab)\times \dotsm}_{m\,\text{factors}}\tag{Definition of an index}
\\[\jot]
&=\underbrace{( a\times a\times \dotsm)}_{ m\,\text{factors}}\times 
\underbrace{(b\times b\times \dotsm)}_{ m\,\text{factors}}\tag{Laws of association and commutation}
\\[\jot]
&=a^{m}\times b^{m}\tag{Definition of an index}
\end{align*}
\end{document}