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This answer in a basic calculus exercise given by a user with 13,721 reputation has at least 5 downvotes. I think it has some sense, if it is not right. At the very least, I would expect someone would explain why such answer is wrong, if it is.

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    $\begingroup$ The user in question is a well-known user prone to posting answers that are... subpar. In this case, I just added myself a sixth downvote for this one-line useless hint. The fact that the user even managed to get 13k rep is a testament that reputation merely measures the quantity of participation to the site. $\endgroup$ – Najib Idrissi Nov 29 '15 at 13:18
  • $\begingroup$ @NajibIdrissi, that's the seventh downvote. I wonder who upvoted. $\endgroup$ – Element118 Nov 29 '15 at 13:19
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    $\begingroup$ Downvotes measure more than incorrectness. If you have a mouse and hover over the down arrow, you see that it mentions the answer lacking research effort, being unclear, or being not useful. I emphasized the last option because it is the likely reason for the downvotes. The answer has been deleted since the question here was asked, so only users with sufficient rep will see the deleted answer. It reads in full: "HINT: with the rules of L'Hospital you will get 0" $\endgroup$ – Carl Mummert Nov 29 '15 at 13:25
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    $\begingroup$ That answer is wrong (or at least very misleading). One should downvote these answer. $\endgroup$ – user99914 Nov 29 '15 at 14:11
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    $\begingroup$ should we find 13,721 reputation suspicious, instead? :) $\endgroup$ – Mirko Nov 29 '15 at 15:58
  • $\begingroup$ Thanks for all your comments. I'm tagging @Mirko because he/she is funny :) $\endgroup$ – user198044 Nov 29 '15 at 22:30
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    $\begingroup$ Related: Serial downvoting risk from review queues. $\endgroup$ – hardmath Nov 30 '15 at 16:49
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The reputation score of the user who posted the answer is completely irrelevant. What matters is the quality of the answer. Five downvotes on a good answer are suspicious whoever posted the answer, and five (or more) downvotes on a poor answer are not suspicious.

The answer in question is at least completely unhelpful. The straightforward way to apply l'Hospital's rule here does not lead to the desired conclusion. If we apply it directly to the expression

$$\frac{1}{h}\int_0^h f(t)\,dt,$$

where the integrand is a function that is continuous except at $0$, then we obtain

$$\frac{\frac{d}{dh} \int_0^h f(t)\,dt}{\frac{d}{dh}h} = \frac{f(h)}{1} = f(h),$$

and that doesn't lead anywhere if $\lim\limits_{h\to 0} f(h)$ doesn't exist as is the case here.

One can apply l'Hospital's rule after a transformation, but anybody who directly sees which transformations would lead to a situation where applying the rule helps wouldn't need a hint anyway.

The downvotes were completely justified here.

At the very least, I would expect someone would explain why such answer is wrong, if it is.

Sure, that would be nice. But people have limited patience. After a few hundred fruitless comments on a certain user's posts, one just gives up and votes down - and sometimes votes to delete - without bothering to comment any more.

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  • $\begingroup$ Daniel Fischer, thanks for your answer. Relevant fact: "The user in question is a well-known user prone to posting answers that are... subpar." $\endgroup$ – user198044 Nov 29 '15 at 22:31
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    $\begingroup$ Thanks for posting this so I didn't have to. How tiresome to explain this over and over again. $\endgroup$ – Ron Gordon Nov 30 '15 at 1:36
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    $\begingroup$ It is perhaps worth mentioning the speed with which the User posts "answers" after the question is asked. In this case six minutes elapsed from the Q to the A. At one time I studied this pattern and tried to use the evidence to persuade the User to give more thoughtful responses, if indeed it were intended to offer them as Answers per se, but to no effect. $\endgroup$ – hardmath Nov 30 '15 at 16:46

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