00} \, s^0.\end{aligned}$$ This implies $$\begin{aligned} &\int_0^\infty \varepsilon^{n-0} \, (\varepsilon^0 + r^0)^{-n} \, r^{n+0} \, \Big [ 0 \, f(r^0) \, f'(r^0) + r^0 \, f'(r^0)^0 \Big ] \, dr \\ &= 