Does really nobody have an idea? Or a hint? I am completely stuck . I would be thankful for any answers...
Bumping, which is what this post is, is against the rules here and in this case unnecessary you have not recieved an answer because your notation for the volume (and surface) over which the integrals are to be evaluated are not clear. So just provide more explanation in a follow-up post.
Sorry, i did not want to be impatient, i was just interested . And sorry for that mistake, it should of course be the ball around with radius r, i will change that.
But i have a solution: as both functions are harmonic (log|x| being the real part of a holomorphic function) one can use the mean-value theorem which gives the following values for the integrals: