彭赛列？

guanmo1

如图

色k

钓鱼题吧属于是🙄

guanmo1

色k 发表于 2023-1-29 20:27
钓鱼题吧属于是🙄

钓鱼题是啥意思？

hbghlyj

guanmo1 发表于 2023-1-29 14:24
钓鱼题是啥意思？

引证释义
这帖引用的AOPS
楼主把原题$\ln \left(1+\frac{1}{n}\right)\ln \left( 1+\frac{1}{2n}\right)\ln\left( 1+\frac{1}{2n+1}\right)$错抄成了$\ln \left(1+\frac{1}{n}\right) \left( 1+\frac{1}{2n}\right)\left( 1+\frac{1}{2n+1}\right)$
5#怀疑题目有问题, 他说

So something was fishy; the statement was incorrect (as very weak for IMC), and now has been amended. Is that a reason to rate this post? or someone thinks fishy is too strongly (smelling) a non-mathematical ejaculation?

在Using Fourier cosine/sine integral , compute an integration 怀疑题目有问题, 评论:

take $x=0$: the rhs equals 0 whereas the lhs doesn't even exist. by continuation to finite but small $x$ you see that something is fishy here

在Determine if $\sum\limits_{n=1}^{\infty} e^{-\sqrt{n}}$ converges. 怀疑解法有问题:

Is this the correct method? Seems fishy to me...

在Proof Verification怀疑最后一个不等式:

That last equality is fishy... I'm sure someone will comment on this; that is, the contradiction is in the fact that the limit does not exist, not that 1/0 is undefined.

在词典中, fishy的解释是 令人怀疑的。

kuing

guanmo1 发表于 2023-1-29 21:24
钓鱼题是啥意思？

就是那种看似是普通的考试题，但实际上水很深，不是一般人能玩得来嘀。

比如 “求 `\dfrac a{b+c}+\dfrac b{a+c}+\dfrac c{a+b}=4` 的正整数解” 就是一道很经典的钓鱼题。

kuing

看这帖：zhihu.com/question/345570735
当年只有两问，a, b 还有具体数值，现在变成四问，椭圆还一般化了。
这从钓鱼的角度来说，显然当年的能钓到更多人，现在反而没那么像考试题，因为哪有那么多问的😅

kuing

【解析几何】四切线难题——一道经典钓鱼题的探究：
zhuanlan.zhihu.com/p/358605728

看到链接中间那个 `\left( \frac{1-uv}{1+uv},\frac{u+v}{1+uv} \right)` 才想起咱论坛上也扯过耶：
kuing.cjhb.site/forum.php?mod=viewthread&tid=7249

hbghlyj

Lectures on Poncelet's theorem: youtube.com/watch?v=P7E_YOiuDvI
Professor Joe Harris from Harvard University gave a talk at the Columbia Undergraduate Math Society on "Poncelet's closure theorem".

Abstract: Poncelet's closure theorem is an answer to the question, "Given two conic curves in the plane, when is there a polygon inscribed in the first and circumscribed around the second?" Originally proved with some difficulty in the early 19th century, it turns out to be relatively transparent from the point of view of algebraic geometry as it developed over the next century, illustrating some of the value of those developments.

Other videos of Joe Harris: youtube.com/playlist?list=PLTWOVL6OX7hCIFAbbE4q0aSCrRv4aUxax
the Eilenberg lectures: youtube.com/playlist?list=PLj6jTBBj-5B_QE35IEQgLkkEct0Dk8GG6