# Issues with Systeme

\documentclass[12pt]{article}

\usepackage{systeme}
\usepackage{amsmath}

\begin{document}
...

$\systeme*{(x+y)\sqrt{xy}=504,x^2+6xy+y^2=2016}$

...
\end{document}

I'm getting a compiler error and the message is in French... The error seems to occur after I type "6xy" or just "xy" after the "6."

Anyone know what's wrong?

• Welcome to TeX.SX! I'm afraid that systeme only supports linear systems. – egreg Mar 27 '16 at 0:21
• Welcome to TeX.SX! You can have a look at our starter guide to familiarize yourself further with our format. – Reinstate Monica - M. Schröder Mar 27 '16 at 0:26

@egreg is right, it only works for linear system.

The error you get is described in the documentation (footnote 2 page 1 of http://mirror.ibcp.fr/pub/CTAN/macros/generic/systeme/systeme_doc_fr.pdf) It means that system's algorithm find two instance of the same unknown (in that case x) in one equation. Thus the algorithm cannot align correctly your terms.

To do it, i suggest you to use another environment:

\documentclass[12pt]{article}
\usepackage{systeme}
\usepackage{amsmath}

\begin{document}
\left\{\begin{aligned} (x+y)\sqrt{xy} &= 504 \\ x^2+6xy+y^2 &= 2016 \end{aligned}\right.
\end{document}

• I wouldn't even try aligning the equals sign, but that's a question of personal taste. – egreg Mar 27 '16 at 8:42