\displaystyle[br]\begin{equation*} \frac{\mathrm{d}}{\mathrm{d}x} \ln \left(1 - \frac{1}{x^7}\right) = -\frac{7}{x(1-x^7)}\end{equation*}
\displaystyle[br]\begin{equation*} \frac{\mathrm{d}}{\mathrm{d}x} \ln \left(1 - \frac{1}{x^7}\right) = -\frac{7}{x(1-x^7)}\end{equation*}