Figure

$\dfrac{d}{dx}x^{-1}=-x^{-2}=-\dfrac{1}{x^{2}}$
$\dfrac{d}{du}\!\left( \dfrac{1}{u^{2}}\right) =\dfrac{d}{du} u^{-2}=-2u^{-3}=-\dfrac{2}{u^{3}}$
$\dfrac{d}{ds}\!\left( \dfrac{4}{s^{5}}\right) =4\dfrac{d}{ds} s^{-5}=4\cdot \left( -5\right) s^{-6}=-20s^{-6}=-\dfrac{20}{s^{6}}$