This is a wrong answer: math.stackexchange.com/a/4290804/42969. The first step (computing the derivative) is already wrong. I wonder why it was unaccepted and accepted again. – The other answer to that question is plagiarized.
@user21820 I cannot close-vote this annyoing twin-prime nonsense probably because the question was reopened. What you said below about D11, can here also said about D1.
Does anyone know why we cannot see anymore whether we have delete-voted a specific post ? It is very annoying to try to delete posts one has already delete-voted.
@Peter: Okay I managed to find out where you are seeing the information other than when attempting to vote: it was in a tooltip that I never actually see because it takes too long to show up. So I'm sorry I was wrong.
@LalitTolani Yes it is. I acted earlier. Thanks for point out the post. (Note, your link points to an answer, not the question, but I understood. We ask answerers to not answer PSQs.) Thanks again.
@user21820 We could see, on deleted posts, for those with sufficient rep, via the edit history or time-line, who voted to close, and who voted to delete, and, if relevant, who voted to reopen or undelete. I'm thinking that's what @Peter meant. But in any case, in rejecting the mere idea that we could see if we previously voted to delete, after a post is undeleted, you decided Peter was wrong. Peter is correct that with the relevant link, the time-line reveals voters to delete, as well.
