![分数中的空格分母](https://linux22.com/image/366964/%E5%88%86%E6%95%B0%E4%B8%AD%E7%9A%84%E7%A9%BA%E6%A0%BC%E5%88%86%E6%AF%8D%20.png)
平均能量损失
\documentclass[a4paper,12pt]{book}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage[svgnames]{xcolor}
\usepackage{empheq}
\definecolor{formula}{RGB}{255,255,170}
\newcommand*\mybox[1]{%
\colorbox{formula}{\hspace{1em}#1\hspace{1em}}}
\newcommand{\denklem}[1]{\begin{empheq}[box=\mybox]{align}{#1}\end{empheq}}
\begin{document}
\denklem{\frac{V}{\left(\dfrac{20}{9}\right)}=\frac{140-V}{20}}
\end{document}
左右分母上方的空间不相等。如何才能使之相等?
笔记: 我找到了如下解决方案。是这样的吗?那么总是这样做吗?
\denklem{\frac{V}{\raisebox{-1.5ex}{$\left(\dfrac{20}{9}\right)$}}=\frac{140-V}{20}}