deletions | additions       diff --git a/begin_equation_2_begin_align__.tex b/begin_equation_2_begin_align__.tex  deleted file mode 100644  index 5cf9803..0000000  --- a/begin_equation_2_begin_align__.tex  +++ /dev/null 
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\begin{equation}  (2)\;  \begin{align*}  % d/dy  \frac{\partial}{\partial y}: \;  % u*u_x  u \frac{\partial u}{\partial x}   \to  \frac{\partial}{\partial y} \left( u \frac{\partial u}{\partial x}\right)   = \frac{\partial u}{\partial y} \cdot \frac{\partial u}{\partial x} + u \frac{\partial^2 u}{\partial x \partial y}   &= \frac{\partial}{\partial y}\left[ \left( - \frac{\partial \zeta}{\partial y} \right) \cdot \frac{\partial}{\partial x} \left( -\frac{\partial \zeta}{\partial y} \right) \right] = \\  %newline   &= \frac{\partial^2 \zeta}{\partial y^2} \cdot \frac{\partial^2 \zeta}{\partial x \partial y }   + \frac{\partial \zeta}{\partial y } \cdot \frac{\partial^3 \zeta}{\partial x \partial y^2}\\  %newline  % d/dx  \frac{\partial}{\partial x}: \;  % u*v_x  u \frac{\partial v}{\partial x}   \to  \frac{\partial}{\partial x} \left( u \frac{\partial v}{\partial x}\right)   = \frac{\partial u}{\partial x} \cdot \frac{\partial v}{\partial x} + u \frac{\partial^2 v}{\partial x^2}   &= \frac{\partial}{\partial x}\left[ \left(- \frac{\partial \zeta}{\partial y} \right) \cdot \frac{\partial}{\partial x} \left( \frac{\partial \zeta}{\partial x} \right) \right] = \\  %newline   &= - \frac{\partial^2 \zeta}{\partial x \partial y} \cdot \frac{\partial^2 \zeta}{\partial x^2 }   - \frac{\partial \zeta}{\partial y } \cdot \frac{\partial^3 \zeta}{\partial x^3 }\\  \end{align*}  \end{equation}