# Sqrt with fraction in root argument [duplicate]

Possible Duplicate:
Nice-looking p-th roots

How can I move the root higher for this formula ? The fraction in the root is typeset to low:

\documentclass{minimal}
\begin{document}

$\sqrt[\frac{1}{3}]{\frac{4}{4.2}}$

\end{document}


the result of the document is

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## marked as duplicate by percusse, Thorsten, Jake, Gonzalo Medina, Harish KumarAug 27 '12 at 13:44

\documentclass{article}
\usepackage{amsmath}
\begin{document}

$\sqrt[\leftroot{-2}\uproot{5}\frac{1}{3}]{\frac{4}{4.2}}$

\end{document}


Unit for the macros is mu (mathunit 1mu=1/18em)

See also page 59 of mathmode document -> texdoc mathmode

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It is better. I have other question: how do the commands \leftroot and \uproot work? Is there any formula to calculate their arguments, depends on the fraction? –  lazyboy Aug 27 '12 at 13:27
the insert only vertical and/or horizontal space which doesn't depend to the following argument –  Herbert Aug 27 '12 at 13:35