deletions | additions       diff --git a/begin_equation_2_begin_align__.tex b/begin_equation_2_begin_align__.tex  index 9c8fe11..6d1e2f8 100644  --- a/begin_equation_2_begin_align__.tex  +++ b/begin_equation_2_begin_align__.tex 
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% d/dy  \frac{\partial}{\partial y}: \;  % u*u_x  u \frac{\partial u}{\partial t} x}  \to  \frac{\partial}{\partial y} \left( u  \frac{\partial u}{\partial t}\right) x}\right)   = \frac{\partial u}{\partial y} \frac{\partial u}{\partial x} + u \frac{\partial^2 u}{\partial x \partial y}  &= \frac{\partial}{\partial y}\left[ \frac{\partial}{\partial t} \left( -\frac{\partial \zeta}{\partial y} \right) \right]   = - \frac{\partial^2 \zeta}{\partial y^2} \\  %newline