Harmoniskt medelvärde

\[ \bar{x} = n\left( \sum_{k=1}^{n} \frac{1}{x_k} \right)^{-1} =
\frac{n}{\displaystyle \sum_{k=1}^{n} \frac{1}{x_k}} =
\frac{n}{\frac{1}{x_1} + ...+ \frac{1}{x_{n-1}} +\frac{1}{x_n}
} \]