By computing ∇(1/r) show that
∫∇²(1/r).dV = -4Pi if the volume 'V' is a sphere containing the origin.
The Attempt at a Solution
∫∇²(1/r).dV = ∫∇(1/r).dS But I cant differentiate (1/r) since the sphere contains the origin. Im wondering if there's any other way to tackle this.