Question: I've seen a lot of questions of rather elementary limits (most of them 'highschool' level), where users answer saying things like

> 
> "Note that $\sin x =\sum \frac {(-1)^n}{(2n+1)!}x^{2n+1}$, then it's rather trivial $\dots$"
> 
> 
> 

Or

> 
> "Just remember that $\sqrt x \in o(x)$, then $\dots$"
> 
> 
> 

I'm always disappointed at seeing answers like that, it's utterly obvious they'll be useless for the one asking the question (and most of the times it's really kind of "killing an ant with a nuclear bomb").

What do you guys think?

Answer: 
I think such answers should not be downvoted merely because they are beyond the presumed understanding of the OP. (There may of course be other reasons to downvote the answer.) In the first place, "answers are for everyone." I can't count the number of times that I've learned something here because someone else introduced a more powerful technique than I was aware of. (Well, obviously it's *countable*, but—oh, you know what I mean.) In the second place, who can say for sure what the OP knows, or can apprehend once shown?

As for frowning upon such answers—to be sure, no one can know if you frown upon something, but in my opinion, it's not productive to censure someone (not censor) for using a sledgehammer instead of a flyswatter. My countersuggestions:

* Let the OP comment on the answer if they don't find it helpful; their feedback is more likely to elicit a positive response from the answerer than someone from the peanut gallery.
* Upvote the answers you *do* approve of, rather than downvote the one you don't.
* If no one else has provided a more elementary solution, it may behoove you to add one.
In general I won't down vote an answer just because the answer is an overkill. That kind of answers might provide the asker a new way of thinking the problem that (s)he never sees before (like asymptotic equivalent in your examples).

I'll, however, consider down-voting an answer if the answer use a technique that the question explicitly stated to not use (e.g. Use L'hopital when it's stated in the question that it's not allowed).

Contrary to what you think, the community seems to dislike the opposite- trying to crack a hard problem using elementary approach while using more advanced tool can yield a simpler and more natural solution. For example, the following answers I wrote that got down-vote(s).

[example 1](https://math.stackexchange.com/questions/972765/what-is-the-minimum-value-of-tan2a-2-tan2b-2-tan2c-2-where/972798#972798)

[example 2](https://math.stackexchange.com/questions/1639327/in-need-of-assistance-with-evaluation-of-a-tricky-limit/1639351#1639351)

[example 3](https://math.stackexchange.com/questions/1648482/how-to-find-approximate-value-of-1-01e1-010-99-2/1648494#1648494)