Quantcast
[ 3 / biz / cgl / ck / diy / fa / g / ic / jp / lit / sci / tg / vr ] [ index / top / reports / report a bug ] [ 4plebs / archived.moe / rbt ]

Support us on Patreon!

/sci/ - Science & Math


View post   

[ Toggle deleted replies ]
File: 850 KB, 1000x1024, prob.png [View same] [iqdb] [saucenao] [google] [report]
9765300 No.9765300 [Reply] [Original] [archived.moe]

You should be able to solve this problem (standard for highschool students in countries where people poo in the loo)

>> No.9765303

>>9765300
diverges because odd

sin term is irrelevant

>> No.9765305

>Reminder: /sci/ is for discussing topics pertaining to science and mathematics, not for helping you with your homework or helping you figure out your career path.

>If you want help with your homework, go to /wsr/ - Worksafe Requests.

>> No.9765307

Please stop being a faggot on this board, just look up calc 2 on the interwebs.
saged

>> No.9765315

>>9765300
It has an over-harmonic majorant, so it converges.

>> No.9765317

>>9765307
>faggot
Why the homophobia?

>> No.9765321

http://mathworld.wolfram.com/FlintHillsSeries.html
>It is not known if this series converges

>> No.9765324

>>9765307
>just look up calc 2
>>9765303
>diverges because odd
>>9765315
>It has an over-harmonic majorant, so it converges
Why do all of you idiots pretend to know more than you actually do?

>> No.9765335

>>9765324
You're right, I'm an idiot
t. >>9765315

>> No.9765366

>>9765300
>(standard for highschool students in countries where people poo in the loo)
the funny thing is indians slaughter whites in math scores, that's why they're taking all your fucking jobs

>> No.9765369
File: 2.17 MB, 1280x1530, clownbitch.png [View same] [iqdb] [saucenao] [google] [report]
9765369

>>9765300
[eqn]\sum_{n\in\mathbb{Z}}f(n) = \frac{1}{2\pi i}\int_\mathbb{C}dz f(z)\csc(\pi z)[/eqn]

>> No.9765371

>>9765366
We could easily fight back....if we valued cheating.

>> No.9765377

1/(n^3sin^2n)<=1/n^3 for all n. So yes, it converges.

>> No.9765382

>>9765377
>1/(n^3sin^2n)<=1/n^3
>[math]|\sin(x)|\leq 1 \implies \left|\frac{1}{\sin(x)}\right| \leq 1[/math]
LMFAO

>> No.9765383

>>9765366
they take jobs because they'll work for $2/hour you mongoloid

>> No.9765418

>>9765366
Work with poos daily. Literal walking calculators, but literal calculators. Cannot under any circumstance extrapolate, conceptualize or apply calculations to ill-constrained equations (ie. reality). Must be spoon fed any and everything needed before "hard" math, results must be evaluated after

>> No.9765484

>>9765371
>>9765383
>>9765418
bitter

>> No.9765732

>>9765307
>just look up calc 2 to solve this unsolved problem

>> No.9765751

>>9765321
Find out then idiot

>> No.9765754

>>9765369
>infinity = infinity
ok

>> No.9765759

>>9765300
multiuply the whole thing by 1 to get rid of the numerator, and then it's simple from there

>> No.9765760

>>9765484
>say some dumb shit
>people respond to you
>"hahahaha you must be all so stupid and bitter to reply to a retard like me"

nice self worth

>> No.9765768

>>9765369
f(n) is odd, so that trick won't work here.

>> No.9765775

>>9765300
Wait isn't this an unsolved problem? I have seen this before. I believe it follows from the normality of pi.

>> No.9766025

>>9765300
[math] \sin^2{(x)} [/math] will always be at most 1 so you can remove the term from the expression, henceforth its leaves you with [eqn] \displaystyle \sum_{n = 1}^\infty \frac{1}{n^3} = \Zeta (3) [/eqn]
Q.E.D

>> No.9766032

>>9765300
sum of 1/n^3 converges so if you multiply by a sine term it converges as well because sin(x) <= 1
am I missing something?

>> No.9766034

>>9766025
>>9766032
The important terms are those where the sine is small since it's in the denominator.

>> No.9766054

[eqn]\forall n\,\in\,\mathbf N^*,\,0 \;<\; \frac1{n^3\, \left(\sin\,n\right)^2} \;=\; \underset{n\;\to\;\infty}O \left(\frac1{n^3}\right)[/eqn]
and [math]\sum_{n\;\geqslant\;1}\frac1{n^3}[/math] is convergent, Q.E.D.

Any more homework, OP?

>> No.9766152

>>9765300
Probably converges, being an odd harmonic, even if I'm not even sure that [math]\frac{1}{sin^2(n)}[/math] is continuous. Should be for any integer value, since pi/2 and 3pi/2 aren't integers?
>>9766054
If you want some homework, try your hand at
[math]\lim_{n\to \infty}\frac{sin(\frac{3}{n^n} + \frac{2}{n!})}{log(1+log(1-sin(\frac{5}{n!})))}[/math]

>> No.9766372

>>9766152
Alright, actually give me a hand for this one tho
[math]\displaystyle \lim_{n\to\infty}\frac{sin(\frac{3}{n^n} + \frac{2}{n!})}{log(1+log(1-sin(\frac{5}{n!})))}[/math]
It is trivial to show that the denominator can be reduced to [math]\displaystyle \frac{5}{n!}[/math] using the known limits for [math]\displaystyle \lim_{n\to\infty}\frac{log(1+a_n)}{a_n}=1[/math] and [math]\displaystyle \lim_{n\to0} \frac{sin(a_n)}{a_n}=1[/math] with [math]a_n\to0[/math]

but what the fuck do I do to the numerator? am I missing something?

>> No.9766375

>>9765300
Lmfao there are actually people in this thread unironically using comparison test.

>> No.9766386

This thread has made me realize how retarded /sci is. I don't spend a lot of time on this board so I wasn't able to gauge the relative intelligence but dear fucking god. It approaches 0. You can literally just look at it quickly and see that. You don't need these retarded as long proofs. This is so basic that inspection and high school level math is literally all you need. I've literally lost all faith. Half of you need to unironically neck yourselves.

>> No.9766401

>>9766386
you should leave then, this board is for intellectuals only

>> No.9766433

I love how /sci/'s true nature shows in threads like these. Post a seemingly simple problem and all the so called 150 IQ geniuses come out of the woodwork thinking "hey, I can do this", because they passed calc 1. Of course the retards are all wrong and even manage to overlook the posts that spell out for them it's an unsolved problem.

>> No.9766439

>>9765484
cringe

>> No.9766447

>>9766386
Motherfuck. 1/n approaches 0 too and does not converge as a series.

>> No.9766451

>>9766433
that's the point of the threads like these

>> No.9766458

>>9766386
Nice bait.

>> No.9766494

>>9765300
Kek'd at all the brainlets in this thread who remove the sine because it's < 1.

HEY IDIOTS THE WHOLE POINT IS THAT ITS VALUE CAN BE 0

>> No.9766518

>>9766494
>ITS VALUE CAN BE 0
No, it can't. The zeroes of the sine function are [math] \pi \mathbb{Z} [/math].
Suppose you had an [math] n \in \mathbb{N} \setminus \{0\} [/math] and [math] k \in \mathbb{Z} [/math] with
[eqn] n = \pi k [/eqn] then you could divide by [math] k [/math] to get
[eqn] \pi = \frac{n}{k} \in \mathbb{Q} [/eqn]
which is impossible since [math] \pi [/math] is irrational (the proof that [math] \pi [/math] is irrational has been left to the reader as an exercise).

>> No.9766522

>>9766494
only if n is irrational, as sin is only 0 for [math]\frac{(2k+1)\pi}{2},k\in\mathbb N[/math]
it can approach 0 for great numbers, but I don't think it'll ever be 0

>> No.9766543

>>9766518
>>9766522
But there could be values for which n^3(sinn)^2 < 1 for instance.

>> No.9766550

>>9766543
such as?

>> No.9766559

>>9766550
n = 3

>> No.9766572

>>9766550
And furthermore n = 104347 nets us less than 7.

>> No.9766588

>>9766550
>>9766572
n=355 nets .04!

>> No.9766594

>>9766433
There is a selection bias effect going on, though. The people that correctly note that they can't solve it, mostly don't post in the thread in the first place. Which makes the thread a very misleading place to gauge the relative proportions of those two groups.

>> No.9766597

>>9766594
Yeah, well that's the internet at large. Still amusing though.

>> No.9767406

doesn't work with n=pi because sin(pi) is zero

>> No.9767408

>>9767406
OP obviously will not recover from thid air tight argument.

>> No.9767459

>>9765300
It really says a lot about the state of this sub that this post got so many unironic replies. I guess summer has begun.

>> No.9767534

>>9767459
The biggest influx is during the winter though.

>> No.9767551
File: 96 KB, 1080x793, uwjdyhzsgvjn5vaj2vdg.jpg [View same] [iqdb] [saucenao] [google] [report]
9767551

>>9765303
>>9765315
>>9765369
>>9765377
>>9766054

>> No.9767588

>>9765300
I'm gonna go with yes, none of the values should be infinite, so the sum should be finite.

>> No.9767599

It's equal to 1 + 1/8 + .... + 1/n^3 at most, and that series converges.

>> No.9767753

>>9765300
this is pretty obvious
apply the steps of the extended euclidean to 1 and pi
as n approaches infinity, the general euclidean division step will produce a smaller remainder that is 61% ( [math]\frac{1}{\varphi}[/math] %) of the previous remainder's length. This approaches 0 exponentially, so it would be easy to find [math]n[/math] such that [math]n*1 - m*pi < \frac{1}{n\sqrt{n}}[/math]
because sin(x) is close to x when x is close to a multiple of pi, we will always find n such that
[eqn]\frac{1}{n^{3}sin(n)^{2}} > \frac{1}{n^{3}[\frac{1}{n\sqrt(n)}]^{2}}=1[/eqn]
the general term doesn't approach 0, so the series does not converge

>> No.9767755

>>9765317
nigger faggot

>> No.9767756

>>9767753
*extended euclidean algorithm for real numbers

>> No.9767757

>>9765300
Idk if it converges or not.
Two things could be tried to prove divergence:
1) show that for every e>0 there exists an n such that (n^3)sin(n)^2 < e.
2) show that for some e>0 there exist infinitely many n such that (n^3)sin(n)^2 < e.

Such a proof would probably involve understanding rational approximations of pi.

>> No.9767789

>>9765321
>>9767753
Flint Hill is a retard

>> No.9767914

>>9767753
>as n approaches infinity, the general euclidean division step will produce a smaller remainder that is 61% ( 1/φ %) of the previous remainder's length. This approaches 0 exponentially
citation?

>> No.9767937

>>9765321
I'd lean towards no. A single instance of sin being closer to 0 than n^3 is larger than zero results in the series making a non-convergent jump in value. As n -> infinity, I don't see any evidence that these jumps in value would ever completely vanish.

Though I guess that it would depend on exactly what pi is. If there's some tendency for multiples of pi to never get sufficiently close to whole numbers, then it would converge.

>> No.9767943

Was originally going to chastise OP for being a faggot and posting an open problem, but this thread has given me too many keks at this point. Not bad.

>> No.9768029

>>9765324
>all of you idiots
>idiot
>some dumb shit
>retarded
>HEY IDIOTS
>nigger faggot
this is the /sci/rrhoidal condition of /sci/

>> No.9768074

I play my trap card, having sin(n)^2 use degrees

>> No.9769347

The Answer is yes, because it gets simplified to Sonen∞

>> No.9769352

Shout out to Paa for the calculation help by the way

>> No.9769767

>>9767753
Actually cringed. Like it's not just one of those photography-worthy cringes but this one is physical.

>> No.9769792

It's an unsolved problem, you're all retarded.

>> No.9769971

>>9766386
has to be bait

>> No.9770321 [DELETED] 

>>9765300
The sin term will never be 0, therefore no term will become infinife. All terms are therefore bounded. When n=inf, the term will be 0. Since all terms are bounded and converge to 0 contribution, the sum of the terms must be bounded and therefore the sum will converge. ¶

>> No.9770333
File: 1.32 MB, 450x337, 1522407912651.gif [View same] [iqdb] [saucenao] [google] [report]
9770333

>>9765300
https://mathoverflow.net/questions/24579/convergence-of-sumn3-sin2n-1

>> No.9772385
File: 8 KB, 249x249, 1505836739667.jpg [View same] [iqdb] [saucenao] [google] [report]
9772385

tell me a single theorem or invention you use on a day-to-day basis that came from India

>> No.9772452

>>9772385
Im a big fan of butter chicken and naan.

>> No.9772456

>>9765300
Nope it does not

>> No.9772735

>>9767599
no it's not you retard

>> No.9772868

>>9765300
it diverges in every p-adic field. proof: obvious

>> No.9772875
File: 20 KB, 367x332, 1513498676427.jpg [View same] [iqdb] [saucenao] [google] [report]
9772875

>>9772385
STEM YouTube videos/lectures that are an absolute pain to watch due to the poo accent.

>> No.9774196

>>9772385
curry

>> No.9774218

>>9772385
Contributions of Bose, Mahalanobis, or Meghnad Saha come to mind.

>> No.9774321
File: 33 KB, 771x577, 26219600_459144274504953_4988008329146953707_n.jpg [View same] [iqdb] [saucenao] [google] [report]
9774321

>>9765377
I needed a good laugh today.

>> No.9774744

>>9765300
Converges

>> No.9776313

>>9767937
>non-convergent jump
I wish to learn more about this concept.

>> No.9776323

>>9767599
>It's equal to 1 + 1/8 + .... + 1/n^3 at most
>at most
funny way to spell "at least".

>> No.9776330

>>9772385
zero/our digits/positional writing of numbers.
algorithms for extracting square and cube roots
the original rules of chess

>> No.9776707

>>9765300
[math] \sum \dfrac{1}{n^2} > \sum \dfrac{1}{n^3(\sin{n})^2} [/math]
Since [math]\sum \dfrac{1}{n^2} = \dfrac{\pi^2}{6}[/math], [math]\sum \dfrac{1}{n^3 (\sin{n})^2}[/math] must converge to a value lesser than that
>mfw /sci/ hasn't passed calc II yet

>> No.9776720

>>9772385
The [math] 1+2+3+...= - \dfrac{1}{12}[/math] shitpost

>> No.9776918

>>9776707
>that first line
What?

>> No.9776942

>>9776707
Did you even scroll down the thread a little bit before posting this? There was a link the the (previously open) problem with someone who gave a CORRECT explanation under it

>> No.9776948

>>9765300
You don't own me, I don't have to solve this If don't want to.

>> No.9776954
File: 2.28 MB, 2448x3264, 1527562828371.jpg [View same] [iqdb] [saucenao] [google] [report]
9776954

Have all of you fucktarded autists seriously not just said p test p>1?

Kys

>> No.9777007
File: 214 KB, 750x1334, 6C101263-1AFE-4F1F-A2D3-B67C51F13256.png [View same] [iqdb] [saucenao] [google] [report]
9777007

>>9765300
Seems convergent so yeah

>> No.9777906

Just use the ratio test. You can show that the series converges by the ratio test.

>> No.9777909

>>9776954
It's not a p-series. If it was a p-series you would only have the n^3 term.

>> No.9779242

>>9765300
[math]\sin(n)[/math] can't be zero because if [math] k \times \phi = \n [/math] for positive integer k and n then [math]\phi[/math] is rational
so [math]\frac {1}{\sin^2(n})>=M[/math] for some M and it's obvious that this series converges

>> No.9779316

>>9765300
Direct comparison test. f(X) < Σ1/n^2, which converges, therefore it must also converge.

>> No.9779316,1 [INTERNAL] 

wait everyone heres actually retarded lol this is LITERALLY AN OPEN PROBLEM, ie LITERALLY NO MATHEMATICIAN IN THE WORLD HAS CRACKED IT YET. in fact its tied to the normality of pi, which has famously been known to be difficult as fuck to even begin proving. i fucking hate people who affirmatively say shit when they have literally no knowledge of the topic; it's insulting really

>>
Name (leave empty)
Comment (leave empty)
Name
E-mail
Subject
Comment
Password [?]Password used for file deletion.
reCAPTCHA
Action