(Solved): Using either Cartesian or spherical polar coordinates show that the Laplacian of a central field p ...

Using either Cartesian or spherical polar coordinates show that the Laplacian of a central field potential, \( \phi(r) \), corresponds to \[ \nabla^{2} \phi(r)=\frac{2}{r} \frac{d \phi(r)}{d r}+\frac{d^{2} \phi}{d r^{2}} . \] Then evaluate the Laplacian for the special case \( \phi(r)=r^{n} \). Show all steps of your calculation.