I believe this thread has been beaten to death.

Says that I'm answering to a student request on how to solve a math problem (in a math forum).

First, it's obvious that he has no idea at all on how to solve the question. Fine. That improper integral of thing is not an easy question. I admit it. Therefore, I gave him a plan and helped him by explaining from a to z(It was only an exagerration, wasn't it?) on how to devise that plan, clearly, in many replies.

But he seemed to be only interested in the talking without having the heart to read the instructions and asked one very simple question which was already answered (by me and also other nice senior members) in the previous post, can I, in this instance, merely reply, "I believe this thread has been beaten to death." with no leaving him the hard feeling?

Thanks.

Isabelle

(Edit: Sorry, I should put this post under "General Englishh Vocabulary & Idiom Questions". Apparently, I made a mistake here by clicking the wrong section.)