Below this answer, I wrote "Try to refrain from answering exercises copied and pasted from a textbook or problem sheet, and nothing much else," and the answerer's response was "I could tell, but it was just too easy a question to pass by." ???
I don't think that either this answer or this answer actually addresses the question which was asked. As I commented, both answers seem to assume the result that is meant to be proved.
@XanderHenderson I already voted to close. From what I've seen today in the reviews, today seems to particularly bad wrt the number of low-quality posts that get answered, and the slow rate of close votes.