90

There are occasions when the use of l'Hopital is circular. E.g., when using l'H on $$\lim_{x\to0}{\sin x\over x}$$ you have to differentiate $\sin x$, but to differentiate $\sin x$, you have to evaluate $\lim_{x\to0}{\sin x\over x}$.


65

No, this is not the correct place to post your solution. At best this looks like self-righteous advertising, at worst spam. There are a few caveats and points for discussion here though. This is a Q&A site. Saying "here is my proof" is not a question... The problem of determining if $\pi+e$ is irrational is stated on Wikipedia as being open, ...


60

(My own two cents.) Your post is entitled: I feel mathematically inadequate for this site. What level are the majority of questions? The notions of "(in)adequate for this site" and "level of the majority of questions" need not hold the relation that you suspect. Your first sentence in the body of the post is: I visit this site a lot (even though I ...


58

You should flag for moderator attention and explain what's up. Mods can check the history and see even those things which have been deleted. You should absolutely not engage with that user in any other way. Let moderators handle exceptional incidents like this. Just flag, walk away, and continue to Be Nice on your own.


53

As Jin describes it in the original Design Ideas for Mathematics Site post, it's a Penrose triangle made of cubes, with the corner cubes removed: The absence of the corner cubes makes the "impossible object" illusion somewhat less striking (in fact, I'm not even 100% sure that it's still impossible to construct out of actual cubes), but if you look closely, ...


45

This is THE place. I call this place a "super computer". And it is. It is true that maybe it is a harsh place for newbies, but that is not 100% true. It is harsh only if you ask something that clearly is intended to solve your homework, and your homework is "easy". I think it helps keeping this place orbiting around the genuine, difficult ...


44

Here are some of my experiences talking about math.se in the real world. I knew a well-meaning but struggling sophomore math major who felt too afraid to post a question here. She used the site frequently as a resource by finding questions through Google, but viewed the community as standoffish, with opaque expectations that she was bound to mess up in some ...


40

Personally, I'm against any calculus technique that can be applied without (much) thinking. These days calculus (in North America, at least) is taught in a way that people can get high grades without having the slightest idea of what a derivative or an integral is. In most classes I teach I ask what an integral is, and very rarely do I get satisfactory ...


32

I considered the distribution of (question)-(1st answer) time interval among the questions that received at least one answer. There are about 186600 of such questions in the SEDE database, approximately 87% of all questions. (Thus, multiplying the percentages below by 0.87 will give the percentage among all existing questions.) Executive summary of results: ...


32

The standard reference for this is "Good Subjective, Bad Subjective". Note that when we compare the two description you quoted there remains a gap. On the one end of the spectrum there are those questions whose answers "[can] be objectively evaluated as correct or incorrect," these are not soft questions. On the other end of the spectrum there are those ...


32

First, I want to praise you for asking a good question here! Alas, teachers and professors generally only encourage students to ask "clarification questions," and don't otherwise instruct students how to ask good questions. (Of course every teacher answers questions... a different matter.) There are even cultures in which asking any questions is ...


27

There will never be a time when you don't feel mathematically inadequate, either here or in general, because the essence of mathematics is figuring things out that you don't know yet. Very few of the answers I've written are to questions I knew that I could answer right away. Those for which that is true tend to be the answers I am least proud of. I look up ...


26

From a purely practical point of view: how you answer an older question might be different than how you answer a new question. Is frowned upon to do so? There's nothing frowned upon. The only answers people frown upon here are when people post complete solutions to homework problems where there is no apparent effort in the question to solve the problem. ...


22

In some circumstances questions like "How do I do X without Y" are genuinely intellectual exercises in working without powertools, but in other circumstances they seem more like "I have an aversion to thinking about Y so let's just do it another way." My impression is that the first group is by far the bigger group in general, but for l'Hopital's rule ...


22

I am a person who was "good" at math in high school, but I would definitely consider myself an "enthusiast" rather than a "mathematician". (Somehow I feel that "mathematician" is a serious title reserved for those who do research, while I am merely a student.) For me, Math.SE is the only place where I can ask and ...


20

Sometimes how attractive a question is is also a matter of luck, of who is connected at the time you ask. But in general here are a few tips: Avoid asking ten questions in one (I've seen that) Try to emphasize the point - even if the context requires some terminology and perhaps an unavoidable long text, you can always give a clear and short introduction ...


18

None of these are meant to directly relate to your own questions, but they're things I think about both when asking and answering questions online (although I can always do better). Understand the social contract This is a tricky one to express clearly, partially because it depends a lot on where you're asking the question. In some places, like this site, ...


17

You shouldn't take single downvotes too serious. If you receive many more downvotes than upvotes, something is probably wrong with your question, but I had many questions starting with $1$ or several downvotes which were upvoted some time later. Single downvotes need not be justified, but you will have to live with them on this site. Sometimes, even the ...


15

The existing answers show why such questions should be closed. They are a random collection of personally preferred practices, opinions and anecdotes of little to no value, taken from a self-selected sample that is not representative of anything. "I know a guy who..." This is what such questions generate: enjoyable exchange of personal stories / ...


14

Don't upvote anything that is wrong. In the situation that you are describing, better give an encouraging comment pointing out the mistake. When the answer is corrected, you still can upvote.


14

This is a bit of a meta answer, but let me explain a bit of why a course might not cover l'Hôpital's rule. When I teach calculus I've skipped l'Hôpital for two reasons. First, understanding when using it is and isn't circular is much more difficult than anything else covered in a Calc 1 class. Gerry gave a great example of a subtle circularity, but ...


12

There's a lot that could be said here, but I'll try to answer the actual questions. I'm not entirely sure that they're on topic for meta, but I feel that an answer would nonetheless be useful here. The questions: (copied and pasted from the question for clarity) But for errors that people have already spent so much time inventing a wheel for, how does one [...


11

To answer the question you actually asked: I would say that $\frac{2}{3}$ of the questions on MSC can be answered with a the sophistication of a typical BS degree in math. Of those questions, roughly half are disappointingly trivial, stemming from a questioner just not knowing some terminology or being confused as to how to get started. It is important ...


11

Well, to start with the facts, users are limited to asking 50 questions in a month or 6 questions in a day. Aside from that, provided that your questions are of good quality (and remain well received by the community), it's acceptable to post as many as you wish. From your comment about vetting proofs, it might be worth having a look at this meta thread ...


11

The question that you ask is quite broad, an comments are a bit too terse for discussion-in-detail. As such, I am going to attempt to address your points (1)-(3) in an answer. (1) For most of the SE sites, what are valued in an answer are completeness, good research, and length. Unfortunately, the self-flagging features of M.SE are continually flagging ...


11

The fact that your question was written to be answered by yourself is a red herring here, and has nothing to do with the reception of your question. The first thing you should be asking yourself is "Is my question a good question, per the site guidelines?" My first impression of the linked question—even in the current state—is that it doesn't ...


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