Non-editable png screen shot:

 

 

This is a try inserting a PDF of  Korteweg–de Vries

 

This is the equation in MS Word:
danEquation_test

 

 

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This is using the CodeCogs online equation editor:

\frac{\partial u}{\partial t}=6u\frac{\partial u}{\partial x}-\frac{\partial^3u}{\partial x^3}

 

OK, and now, Jetpack’s LaTeX plugin

\frac{\partial u}{\partial t}=6u\frac{\partial u}{\partial x}-\frac{\partial^3u}{\partial x^3}

\frac{x^2}{1+x}

 

\frac{x^2}{1+x}

 

This is the latex code generated from Apple’s Grapher. Grapher is located in /Applications/Utilities/Grapher.app
\frac{\partial u}{\partial t}=6u\frac{\partial u}{\partial x}-\frac{\partial ^{3}u}{\partial x^{3}}