While not lying to those reading a question, it's certainly disingenuous to not state clearly in a question the intent of posting that question. One of the core reasons people answer questions on this site is to help people who are trying to understand new concepts, and can often exhibit huge amounts of effort into helping people understand difficult ideas.
If a question asker already understands a concept and just wants to see a possibly nicer approach to a problem, then they should say so before someone wastes their time explaining basic concepts, when they're really preaching to the choir. If you have a solution and want the proof checked, write the proof, state so, and use the proof-verification tag. If you have a proof but want to see a proof requiring less machinery, more abstract concepts, or more succinct arguments, write your proof, state so and use the alternative-proof tag.
Closing for the reason of no context means just that - a question should be given sufficient context so that the answerer knows how to frame their answer, at what level of mathematical maturity, at what sufficient level of detail, and how much effort should be spent on finding a novel/aesthetically pleasing proof.
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box if you wish to allow readers to try the problem free of bias. $\endgroup$