deletions | additions       diff --git a/text_xi__k_begin_equation__.tex b/text_xi__k_begin_equation__.tex  index a861d7c..f00f9eb 100644  --- a/text_xi__k_begin_equation__.tex  +++ b/text_xi__k_begin_equation__.tex 
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}  \begin{equation}   x_{k} {x_{k}  = a\cdot x(k)+k\cdot sin(k) + \xi_{k} \nonumber \\ \\}  \end{equation}  \text { 
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}  \begin{equation}  {y_{k} = b\cdot x_{k}+ \eta_{k}}\nonumber \\ \eta_{k}\nonumber \\}  \end{equation}  \text {