Formula_7780

\[\begin{gathered}\frac{\partial^{|m|}}{\partial x_{1}^{m_{1}} \partial x_{2}^{m}} \ln \frac{1}{r} \text { при } n=2, \\r=\sqrt{x_{1}^{2}+\ldots+x_{n}^{2}}, \quad|m|=m_{1}+m_{2}+\ldots+m_{n} .\end{gathered}\]