How can I re-define a fraction line?

Question

I want to redefine by increasing the width of the fraction line.

\documentclass{article}
\usepackage{amsfonts}
\usepackage{amsmath}
\usepackage[utf8]{inputenc}

\begin{document}
$\dfrac{x+y}{x^2-y^2}$\hspace{1cm}$\dfrac{\;\;\;x+y\;\;\;}{x^2-y^2}$
\end{document}

Answer 1

I'd not use \dfrac in inline math normally, but you can define your own command \newcommand\myfrac[2]{\dfrac{\;#1\;}{\;#2\;}} (or better use \frac in the definition)