[Tex/LaTex] Cross partial derivatives with LaTeX


I'm trying to write something simple:

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Not quite sure how to write out the second term (from the left) in LaTeX. Any suggestions please?

Best Answer

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  \frac{\partial^2 f}{\partial y \, \partial x}
    = \frac{\partial}{\partial y} \biggl( \frac{\partial f}{\partial x} \biggr)
  %  = \frac{\partial}{\partial y} \left( \frac{\partial f}{\partial x} \right)
    = (f_x)_y
    = f_{xy}
    = \partial_{yx} f


There is a difference in the spacing between using a \biggl(...\biggr) and \left(...\right) pair. Your choice, although the former is preferred.