How to get a large division symbol?

Question

I'm using:

\documentclass[journal,transmag]{IEEEtran}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{breqn}
\begin{document}
\begin{align}
 something&\left(\sum_{n}\right.\nonumber\\
&\quad\left.\vphantom{\sum_{n}}+y\right)/\left(x\right)^2.
\end{align}
\end{document}

With \vphantom{\sum_{n}} I get the big right parenthesis in the second line which is what I want. How can I get a larger division symbol as well?

Answer 1

I understand it's only an example, but your usage of \left and \right is wrong.

\begin{align}
 something &\biggl(\sum_{n}\nonumber\\
&\quad+y\biggr) \bigg/ x^2.
\end{align}

Answer 2

To get the scaled division symbol, you probably want to use the \left ... \middle ... \right construction:

\begin{align}
 something&\left(\sum_{n}\right.\nonumber\\
&\quad\left.\left.\vphantom{\sum_{n}}+y\right)\middle/\left(x\right)^2\right..
\end{align}