# How to avoid stretching the equation in multline mode when the width is defined?

I would like to achieve:

• the multline equation spans horizontally .7\textwidth
• the first line is aligned to the left side
• the second line is aligned to the right side

So far I have:

Could you explain me how to fix the problem of stretching the equations?

Code:

\documentclass[a4paper]{article}

\usepackage{mathtools}
\usepackage{lipsum}

\begin{document}

\lipsum*[2]

$$\begin{multlined}[.7\textwidth] \shoveleft{a = b + }\\ \shoveright{+ c} \end{multlined}$$

\lipsum*[2]

\end{document}


The closest question that I found does not have this problem...

You just don't want to use \shoveleft and \shoveright.

\documentclass[a4paper]{article}

\usepackage{mathtools}
\usepackage{lipsum}

\begin{document}

\lipsum*[2]
$$\begin{multlined}[.7\textwidth] a = b +{}\\ {}+c \end{multlined}$$
\lipsum*[2]

\end{document}


The empty atoms {} are needed for getting the right spacing.

• Then what is a use case of using shoveleft and shoveright? From the documentation I was sure it is made for such things. – desa Mar 26 '17 at 13:22
• @desa The documentation is quite unclear indeed. – egreg Mar 26 '17 at 13:29
• @desa - \shoveleft and \shoveright start to become useful once the multline and multlined environments contain three or more rows. – Mico Mar 26 '17 at 14:39