This post from 2014 was closed today. I saw it in the 'close votes' queue, but skipped it because I don't know what the convention is (if any) for posts that are so old. If that post was posted yesterday, then I certainly would have voted to close, but I wasn't sure if there was any point in doing so given its age.
If I understand correctly, the 'lacks context' close reason is there in part to discourage people posting homework questions without showing their attempts. In this case, I don't think seeing your six year old post being closed would do much to dissuade you from posting such questions (although it might dissuade others). I only ask this question because someone other than the OP might find that post useful, and there is a slight chance that someone could come along and provide a good answer to that question at a much later time. On the other hand, I think you could make the case that closing these questions demonstrates to people that Math.SE is not a place just for you to post your homework if you haven't put any effort into it yourself.
NB I don't necessarily think that the question I linked to is a homework question. However, it does have the same issue with it that many homework questions have—there is no information about his or her attempts, level of ability, why they wanted to solve this problem, etc.