[Tex/LaTex] Left align text in equation environment (no use of align environment)

alignamsmathequations

I understand that you can left-align text using \intertext{...} inside \begin{align}...\end{align} environment, e.g. this answer.

Is it possible to do the same but inside \begin{equation}...\end{equation}?

The end goal is to wrap the whole environment inside a display formula (\[ \]) as part of bullet point within a list. I've tried wrapping the align environment this way, but for some reason \intertext{...} does not work as the text is squeezed together without spaces.

EDIT: clarifying the question with an example and more context.

First, I should say that I'm trying to do this in org-mode in Emacs, i.e. compiling a org doc a PDF via LaTeX. The equations appear as part of an item in a list, e.g.

- Blah blah blah, then \[\begin{align*} \label{eq1} \text{something text}
   &= \frac{a}{b} \\ &= \frac{a}{c+d} \\ & \intertext{some other text, gives}
   \\ \label{eq2} a &= b+c \end{align*}\]

In other words, I want the block of displayed equations to be centered w.r.t the list item they belong to, and I want the intertext{...} text to be left-aligned w.r.t the start of each list item, or, at least to the left edge of the displayed formula block.

At the top of the .org doc, I have

#+OPTIONS: TeX:t LaTeX:t
#+LaTeX_CLASS: article
#+LaTeX_HEADER: \usepackage{amsmath}

So far, Emacs seems to compile and produces a PDF file, except that the \intertext segment inside the display formula is wrong:

enter image description here

How do I correct it? I am also open to suggestions that utilize something other than a single \begin{align}...\end{align} environment to achieve the same effect inside a list item.

Best Answer

If I complete your fragment to make a document

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

Blah blah blah, then \[\begin{align*} \label{eq1} \text{something text}
   &= \frac{a}{b} \\ &= \frac{a}{c+d} \\ & \intertext{some other text, gives}
   \\ \label{eq2} a &= b+c \end{align*}\]

\end{document}

then TeX produces

! Package amsmath Error: Erroneous nesting of equation structures;
(amsmath)                trying to recover with `aligned'.

See the amsmath package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              

l.7    \\ \label{eq2} a &= b+c \end{align*}
                                           \]
? 

! Package amsmath Error: Invalid use of \intertext.

See the amsmath package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              

l.7    \\ \label{eq2} a &= b+c \end{align*}
                                           \]
? 

! Package amsmath Error: Multiple \label's: label 'eq1' will be lost.

See the amsmath package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              

l.7    \\ \label{eq2} a &= b+c \end{align*}
                                           \]
? 
[1

After an error any typeset output that may be produced is essentially arbitrary and not really to be looked at, TeX recovers from errors only to allow further syntax checking, usually the typeset result is nonsense.

If I fix the errors reported namely align* should not be inside \[, \intertext should be at the start of the line and you shouldn't use \label as the * form is not numbered so there is nothing to reference, I get

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

Blah blah blah, then
\begin{align*}  \text{something text}
   &= \frac{a}{b} \\ &= \frac{a}{c+d} \\
\intertext{some other text, gives}
   \\ a &= b+c 
\end{align*}

\end{document}

which produces

enter image description here