deletions | additions       diff --git a/untitled.tex b/untitled.tex  index a7af44f..3bc5573 100644  --- a/untitled.tex  +++ b/untitled.tex 
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\begin{matrix}  &x_{t+1}=x_{t}+a*t+6.9+E_{t}&\\  &z_{t}=x_{t}+N_{t}&   \end{matrix}\right.  \end{matrix}  \end{equation}