Left-alignment like Fleqn-option only for specific equations

Question

I want to left-align some equations. (Note: I want to align the equations themselves, not code inside of the equations.)

I have the following example code:

\documentclass{scrartcl}
\usepackage{amsmath}
\begin{document}

\begin{equation}
\text{I want to left-align this equation}
\end{equation}

\begin{equation}
\text{and this one,}
\end{equation}

\begin{equation}
\text{but not this one and others.}
\end{equation}

\end{document}

How can I achieve this? The equations don't neccessarily have to be left-adjusted to the left text border, the more important goal is to align them to each other.

Answer 1

You can use the flalign and flalign* environments from amsmath.

\documentclass{minimal}
\usepackage{amsmath}
\begin{document}
\noindent The quick brown fox jumps over the lazy dog.
\begin{equation*}
A = B
\end{equation*}
\begin{flalign*}
C = D &&
\end{flalign*}
\begin{flalign*}
E = F &&
\end{flalign*}
\end{document}

Does not work with \split in equation environment

Answer 2

I wanted to show an eplain version:

\input eplain
\leftdisplays
$$ \hbox{I want to left-align this equation} \eqno(1.1) $$
$$ \hbox{and this one,} $$
\centereddisplays
$$ \hbox{but not this one and others} \eqno(1.2) $$
\bye

because of the following remark from the documentation:

It is usually poor typography to have both centered and left-justified displays in a single publication, though.