I was browsing at MSE and this question came to my eye:

Let $a_{i} \in\mathbb{R}$ ($i=1,2,\dots,n$), and $f(x)=\sum_{i=0}^{n}a_{i}x^i$ such that if $|x|\leqslant 1$, then $|f(x)|\leqslant 1$. Prove that:

I'm wondering, why is this problem statement question so heavily upvoted? I guess it is because it is very difficult question. But I find it somewhat strange that if a question is very difficult, that then suddenly people don't care to know the context you are facing the problem, or the steps you have taken to solve the problem.

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    $\begingroup$ It was upvoted because it is a good and interesting question. I treat such questions different from boring homework questions, and I think most others do too. $\endgroup$
    – Potato
    Commented Oct 16, 2013 at 19:17

1 Answer 1


The OP did leave a comment below the question with some motivation:

by n=3 is IMO 1996shortlist. so I think General n have this . Do not know to have who has this information or Paper? artofproblemsolving.com/Forum/… –

So, it seems this is a generalization of another problem from the International Math Olympiad.

In the end, I think it's better to think of votes as a sort of stochastic process: better questions will have higher vote counts on average, but there is also a lot of variance, so sometimes the vote count will not seem to match the question.

Still, there are several factors that could have applied here:

  • The question is not trivial. Many PSQs are.
  • The OP has reasonable reputation. Many PSQs are asked by very new users.
  • The OP had stated (in the comment) a plausible source and motivation. The statement is not at all thorough, but it is not entirely absent, either.
  • Different people see different questions (this is part of the randomness of voting)
  • 1
    $\begingroup$ Also, there is an active bounty on the question, which probably has drawn more attention to it. $\endgroup$
    – Daniel R
    Commented Oct 16, 2013 at 20:22

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