# Is there a recommended way to typeset fractions (in brackets) in a sentence?

In these two cases the inner brackets are added to avoid ambiguity. I was wondering if there is an alternative to dropping the outer brackets altogether?

...some quantity defined by a quotient ($y / (\Delta y)$) in this case...

...some fractional value (e.g. $z = 1 / (2 x)$)...

• For one, you would want $z = 1 / (2 x)$ instead of z = $1 / (2 x)$, or else the spacing around the = will not be proper. – Steven B. Segletes Nov 27 '17 at 14:58
• The outer pairs of parentheses are there because they enclose what are called "parenthetic remarks". In the first case, the material in parentheses illustrates the term "quotient"; in the secon, the parenthetic remark illustrates the term "fractional value". If you can't stand the use of parentheses in these cases, consider using pairs of commas or pairs of em-dashes, or simply avoid making parenthetic remarks in the first place. My guess is that if you find that you need to make parenthetic remarks from time to time, you'll also find that using parentheses in such cases is quite natural. – Mico Nov 27 '17 at 15:04
• You could actual brackets [ ] or \lbrack and \rbrack for the inner pair. In math mode one uses size differentiation, but here the outer pair are not math symbols. – John Kormylo Nov 27 '17 at 15:08
• I would try to avoid this at all because the slash is not quite common when typesetting mathematical stuff. In display math mode you could use \frac{}{} instead. On the other hand, this might put too much emphasis on a small example. An alternative might be to place such examples in the margin column using a "real" fraction again. – Matthias Nov 27 '17 at 15:21
• @Matthias -- i'm afraid my mathematics skills are not sufficient to discern the difference between 2x and 2\cdot x; if the \cdot were actually present in the expression, then there would be no question of removing the parentheses. – barbara beeton Nov 27 '17 at 18:02

Here are some options:

\documentclass{article}

\usepackage{lmodern}
\usepackage{amsmath}

\begin{document}

\section{Original version}
\par\emph{Slightly modified.}
\par\dots{} some quantity defined by a quotient ($y / \Delta y$) in this case \dots
\par\dots{} some fractional value (e.\,g., $z = 1 / (2\,x)$) \dots

\section{Replacing the outer pair of parentheses}
\par\emph{Might be a good option.}
\par\dots{} some quantity defined by \emph{the} quotient $y / \Delta y$ in this case \dots
\par\dots{} some fractional value, e.\,g., $z = 1 / (2\,x)$, \dots

\section{Using a negative exponent}
\par\emph{Seems even better.}
\par\dots{} some quantity defined by a quotient ($y \cdot \Delta y^{-1})$ in this case \dots
\par\dots{} some fractional value (e.\,g., $z = (2\,x)^{-1}$), \dots

\section{Using a text fraction}
\par\emph{Not recommended because it increases the line spread.}
\par\dots{} some quantity defined by a quotient \big($\tfrac{y}{\Delta y}$\big) in this case \dots
\par\dots{} some fractional value \big(e.\,g., $z = \tfrac{1}{2\,x}$\big), \dots

\section{Using display math style}
\par\emph{May put too much emphasis on the formulae to be embedded.}
\par\dots{} some quantity defined by a quotient
\begin{equation*}
\frac{y}{\Delta y}
\end{equation*}
in this case \dots
\par\dots{} some fractional value, e.\,g.,
\begin{equation*}
z = \frac{1}{2\,x}\,,
\end{equation*}
\dots

\end{document}