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Hi I have the following problem, the Kile under ubuntu does not accept the following structure (simplified):

\begin{eqnarray}
y&=& \left( \frac{1}{x} (a+b) \nonumber \\
&+& (c+d) \right)
\end{eqnarray}

when I put ( ) instead of \left( \right) then it works, but I want the size of the brackets to ...