deletions | additions       diff --git a/begin_equation_3_begin_align__.tex b/begin_equation_3_begin_align__.tex  index 0c6f77d..0c3ec1b 100644  --- a/begin_equation_3_begin_align__.tex  +++ b/begin_equation_3_begin_align__.tex 
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\to  \frac{\partial}{\partial y} \left( v \frac{\partial u}{\partial y}\right)   = \frac{\partial v}{\partial y} \cdot \frac{\partial u}{\partial y} + v \frac{\partial^2 u}{\partial y^2}   &= -\frac{\partial}{\partial \frac{\partial}{\partial  y} \left[ \frac{\partial \zeta}{\partial x} \cdot \frac{\partial}{\partial y} \left( -\frac{\partial \zeta}{\partial y} \right) \right] = \\ %newline   &=-\frac{\partial^2 \zeta}{\partial x \partial y } \cdot \frac{\partial^2 \zeta}{\partial y^2 }   + -\frac{\partial \zeta}{\partial x } \cdot \frac{\partial^3 \zeta}{\partial y^3}\\