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6:01 AM
@Jeff I am not that motivated, but if it is simple xD
 
Well, it's to use a triple integral to solve a volume problem. It's here: math.stackexchange.com/questions/1050979/…
 
@Jeff Looking at it, I would recommend a transformation into spherical or cylindrical coordinates
But I haven't done such problems in a year and a half or so
 
Ha! I already recommended that. But they haven't gotten to that part of the book yet. :(
@Committingtoachallenge It's literally the next section of the text
 
Unfortunately it is 37c degrees(99fahrenheit ) in my house so I am running low on motivation
 
huh?
 
6:04 AM
I think they are using it as motivation for the next part
 
k that's my guess too.
 
Have you considered changing the order of integration
It is sometimes impossible to solve without changing order
 
it came out more complicated when i tried that. maybe i'll add that to the post, too.
do you think i setup the problem wrong?
 
If you can't draw the x,y - x,z - y-z graphs perfectly enclosing the region, you need to rearrange
 
i can draw them all
 
6:08 AM
Out of laziness, I will see if your setup can be integrated by mathematica
 
@robjohn If I post an answer and after getting some up-votes I make it community-wiki. In that case will I loose rep? Will I loose rep if someone down-votes that answer after I make it community wiki?
 
@Integrator No. No.
 
@Integrator as soon as you make it CW, you don't gain or lose rep from it
 
@robjohn and I keep previously earned rep right?
 
@Integrator Yes.
 
6:11 AM
@Integrator yes. As soon as you make it CW, you don't gain or lose rep from it
 
@robjohn That is an indirect implication though.
 
@robjohn @WillHunting Got it. meta.stackexchange.com/questions/11740/…
@robjohn @WillHunting Thanks!
 
@WillHunting no, it directly says that he will not lose rep.
 
@Integrator No problem, 100 dollars.
 
@Jeff It integrates just fine to $16\pi$
 
6:13 AM
@WillHunting ?
 
@robjohn He was also asking about the votes before the wikification, not after.
 
@Jeff E.g. Your integral is fine, you must have just done some step wrong, happens to the best of us :)
 
@WillHunting It's clear now!
 
@Committingtoachallenge is 16pi the correct answer? I really feel like it's setup correctly.
 
@WillHunting I mean everything except 100 dollars
 
6:14 AM
@WillHunting yes, but once it is CW he won't lose rep from that answer.
 
Hey hey
 
Hey @KajHansen I just watched 5 min of Good Will Hunting, my favourite scene.
 
What's your favorite scene? One of my favorites is Will defending himself in the courtroom.
 
@Jeff Your last step evaluates to $8\pi$ so you are off by a factor of 2
 
@KajHansen "It is not your fault"
 
6:16 AM
@WillHunting My favourite scene as well
@KajHansen Hey Kaj how are you?
 
@Committingtoachallenge Fools seldom differ.
 
@KajHansen Ready for those finals :)
@WillHunting ;)
 
@Committingtoachallenge interesting. TY
 
@Committingtoachallenge, I hope so. We've learned two new verb tenses in French this week, and along with those are tons of irregular verbs. Ugh. I will have a lot of studying to do for that.
 
@Jeff The next chapter will be lovely
 
6:17 AM
haha. i know!
 
@KajHansen Oh yeah I forgot you were doing language studies, you know a few don't you(to some extent)?
German and Latin was it, or was that someone else?
 
You're probably thinking of Ted. :) He's definitely a polyglot.
 
@Committingtoachallenge Just to be clear, you put the top line into Mathematica and got $16 \pi$?
 
@Committingtoachallenge Then you put the last line in and got 8 \pi
 
6:19 AM
Integrate[4, {x, 0, 2}, {z, 0, Sqrt[4 - x^2]}, {y, x^2 + z^2,
8 - (x^2 + z^2)}]
16 [Pi]
Integrate[(x^2 - 4) Sqrt[4 - x^2], {x, 0, 2}]
-3 [Pi]
-3 Pi*(-8/3) = 8[Pi]
 
French is my first language, but I'm in an accelerated version right now that's combining two semesters into a single semester. It's definitely nontrivial. Probably the hardest non-math course I've taken here at UGA.
 
Wait your first language preceding English?
 
@Venus no.
 
The first foreign language I'm learning, I should say.
 
Oh okay, haha I was extremely impressed xD
 
6:21 AM
I hope to become proficient in French one day. At least to the extent of reading and writing.
 
(Not to say learning French is not impressive)
I would like that too, but you are a lot closer than I(haven't done much beyond some Duolingo)
Is 99fahrenheit hot for America?
 
@KajHansen Get Assimil's New French With Ease and Using French, these two.
 
@WillHunting, I should. I'm currently sitting on Rosetta Stone myself. I've worked through the first two CD's in the past, but it's been a while. Now that I've gotten a LOT of the theory behind my belt, it would be nice to start over in a more immersive environment to build my working vocabulary up.
 
@WillHunting @robjohn But then will I lose my tag badges,
 
Three days I haven't seen another living person
(Including today)
 
6:24 AM
Plus I'll be taking another French course next semester (which I should probably go ahead and register for right now).
 
@KajHansen Many people think Rosetta Stone is a waste of money. Also, try Routledge's Colloquial French and Colloquial French 2, and Teach Yourself's Complete French and Perfect Your French, these four.
@Integrator Badges are never lost, once obtained.
 
@Integrator you never lose badges
 
@WillHunting, you may be right. It was simply a gift given to me many years ago.
 
@robjohn @WillHunting I think that's not the case about tag-badges
 
balarka thinks i should do dummit and foot, is it good
 
6:27 AM
@Integrator I don't know. Why bother about badges? You can't buy pizza with them.
 
@beginner, woah! Dummit and Foote is a wonderful textbook, but it's borderline undergrad/graduate level in difficulty.
 
Kaj! hey
i found a pdf for it :)
 
Certainly if you have extraordinary willpower and initiative, don't let me stop you though :)
 
@beginner You have not told us your background and motivation, so this question is not answerable.
 
i am finishing grade 5 next week :)
 
6:29 AM
@WillHunting Really? no Pizza? :(
 
@beginner I see. Have you learnt any other more advanced math?
 
By the way, @beginner, I've found abstract algebra to be the most fascinating subfield of math.
 
@WillHunting i am learning vector spaces and subspaces now
 
@beginner From where?
 
6:29 AM
@KajHansen oh really that is good, does it mix with your ramsey number stuff?
 
Not really. At least not directly. But in the big picture, abstract algebra mixes with basically everything to some degree.
 
@KajHansen balarka said it is where groups and modules are
 
@Integrator You don't lose the tag badges you have, but you won't get new ones, in that tag, until you catch up
 
but i dont know what a module is yet
 
6:31 AM
@beginner From where?
 
texts my brother lends me
i dont have his book right now though :(
i think he thinks i will damage it
 
Yeah. There are all sorts of sets that have varying degrees of structure. Groups, modules, rings, fields, etc.
 
i think i am only doing fields at the moment. i just had professor ted confirm my knowledge of subspace sums and direct sums :)!
 
@robjohn Okay, But how do you show posts in chat instead of just link to it?
 
and i said that sums are like spans and direct sums are like a basis(cause they need uniqueness) and he said i was doing really well :)
 
6:35 AM
@Integrator I just linked to it, but since I used the link to your post, it came out as a post snippet. Now that I've added more text, it shows up as a link
 
@robjohn Fine! Thanks!
 
@Integrator yes, and you typed @robjohn. That was enough to change it
 
Keep at it @beginner. Don't forget to give yourself lots of homework. That's how you truly learn math, imo. It's never enough to just read (a trap I fall into all the time).
 
@robjohn is it okay to flag questions for moderator attention to be marked as protected?
 
@KajHansen ted gave me a task to 'use vector methods and dot products to prove some geometry results.' so i am going to do that for fun :)
 
6:40 AM
@Integrator You can but it is weird to flag for it just to be protected.
 
@WillHunting Why?
 
@Integrator Others can mark questions as protected, but I guess if no one else seems to be protecting it, flagging a mod would be okay.
 
Yes! That's a great idea @beginner! One of the things Ted had us do on the first day of class was to show that the medians of a triangle always intersect at a single point using vectors.
 
@robjohn Thanks again
 
@Integrator flagging a mod is usually for more serious infractions.
 
6:42 AM
@robjohn Like?
 
But there are all sorts of problems to try out. For example, show that the diagonals of a rhombus are perpendicular.
 
@robjohn Thank you for answering on my behalf, lol.
 
It's like no matter what you problem you have you just @robjohn and it is solved!
 
@robjohn We use \tfrac for infractions, lol.
 
@WillHunting for small infractions
 
6:44 AM
@Integrator I answered your questions first, lol.
@robjohn We use \dfrac for outfractions.
 
:D
 
@Twink Hi! How is your schoolwork?
 
@WillHunting hi, i failed a course
today
:(
and I'm depressed
 
@Twink Will you lose your funding?
 
yes
it's lost
but I won't give up
I'm gonna get a job
a part-time job
 
6:52 AM
@Twink Hang in there. There can be miracles when you believe.
 
?
like which miracle?
mm :(
 
@KajHansen i think it will be fun and maybe if i do well enough he will give me more problems :)
 
You can always just ask for more. He certainly has no shortage :P
 
@KajHansen he doesnt answer balarka anymore i think, so i will try to be a good student :)
 
LOL, that's a good point.
 
7:02 AM
i think balarka said algebra > geometry and that was why though
 
Ted was telling me this story just today in his office.
 
i wish i knew a professor in person
so you talk about stack exchange in person, that is awesome!
 
haha, yeah
 
have i come up :)?
 
Not yet. Hang out here long enough though...
 
7:06 AM
maybe one day i will be able to talk real math here and you guys won't have left
 
I'll probably be here for years. I enjoy the community.
 
yay, it would be sad to get to know people here and then they all leave
i have to go now though
 
Have a good day! Or night, depending on time zone.
 
cya later :)
 
7:22 AM
any one knows where to search for this: I need to find out relation between zeros of polynomial p1 and p2 on their own, vs. zeros of the combined polynomial (1-z)p1+z*p2 where z is a number between 0 and 1. Actually just knowing the relation between p1,p2 and the combined one p1+p2 will help. Not sure if there is a theory on this I should look for
by trial and error, I found that if p1 and p2 are stable polynomials, then (1-z)p1+z p2 is always stable as well. but need to proof this.
 
7:35 AM
Help!
0
Q: Is F even or odd, what is the period of it?

FreeMind$$F(\theta)=\sin(\theta)\int_{-l}^{l} e^{-ikz\cos \theta} h(z)\,dz$$ We know that $F(\theta)$ is defined on $0\le \theta \le \pi$ and $h(z)$ is defined on $|z|\le l$ What is the period of $F(\theta)$? Is $F(\theta)$ even or odd? What if we change the dummy variable $z$ in the integral? does it a...

@robjohn You the SE angel, please answer!
^^
Another related question,
0
Q: Approximate $F(\theta)=\sin(\theta)\int_{-l}^{l} e^{-ikz\cos \theta} h(z)\,dz$

FreeMind$$F(\theta)=\sin(\theta)\int_{-l}^{l} e^{-ikz\cos \theta} h(z)\,dz$$ We know that $F(\theta)$ is defined on $0\le \theta \le \pi$ and $h(z)$ is defined on $|z|\le l$ and $z$ is real in this case, but it might be complex too! That is all we know, how can we find the $h(z)$ by having knowledge of $...

 
8:17 AM
I hate to say this but algebraic topology is really fun stuff.
Maybe it's not so bad after all, even though I am still going through covering spaces.
@KajHansen It was just a joke, I promise.
 
@BalarkaSen, what was?
 
That algebra > geometry
I didn't really mean it.
 
LOL. I've talked about this joke like thrice today.
And I wasn't even there.
 
Well, Ted told you.
 
Personally, I've enjoyed algebra the most out of any subfield of math I've studied thus far.
 
8:24 AM
Me too. I've enjoyed it even more than number theory, of which I know nothing about.
I don't want Ted to ignore me. cries
 
hahaha
 
@MikeMiller I am trying to find an example of covering maps $p : A \to B$ and $q : B \to C$ with $A, B, C$ path connected such that $r = q \circ p$ is not a covering map. This can be done for non path connected spaces, say, $S^1 \times \Bbb N \to S^1 \times Bbb N \to S^1$, the latter map being projection and the former map just wraps each circle $n$ time around another, $n$ goes to $\infty$.
Maybe $r$ is always a covering space when $A, B, C$ are locally path connected but I am unsure.
What we know is that $\pi_1(p)(A, a_0)$ is inside $\pi_1(B, b_0)$ and $\pi_1(q)(B, b_0)$ is inside $\pi_1(C, c_0)$
"but then I can't"
@KajHansen It's past bed time there, isn't it?
 
Ugh...
Yes
 
what is le time?
 
3:40ish
AM
 
8:35 AM
it's barely afternoon
 
Does anyone know how to fix their sleeping patterns?
I usually sleep for from 9pm-4am each night, but I slept for 11 hours two days in a row, and I woke up at 12pm...
 
Stay up for 2-3 days straight and then go to bed at a reasonable hour on the 3rd day. I speak from experience from when I took differential geometry, 2nd semester abstract algebra, and mathematical methods in physics all at once.
 
SHEESH @Kaj
 
That was once my method, but now I am really bad at staying up one night
 
That's a whole load of subjects.
 
8:38 AM
Oh, your sleeping trouble are nowhere near as severe as mine.
 
I had series insomnia as a kid
I stayed up for 6 days once, and I had to go to the doctors and get sorted
 
I have insomnia too
 
I then had depression for years, and now my sleep problems and depression seem long gone
I think it might be social isolation
I will stay up tonight I guess, noone here to need to be properly concious tomorrow for
 
@KajHansen Did you study inverse limits anymore after I roughly said what p-adics are? Or are you still going though the BS PDE stuff?
 
@KajHansen I guess I was hoping for some special trick that I had suspected didn't exist
 
8:41 AM
You mean ODEs, haha. Not PDEs. I have them for another week, and then I have a month of break to study what I want.
 
Can someone here me help to understand this joke. Sorry, this question is unrelated to math
I think it is US joke, but I don't get it
 
@KajHansen Cool beans.
 
@Venus, it's implying the guy is cheating on his girlfriend.
 
@KajHansen What did the guy say in the end of video? I can't hear it nor understand it
 
8:45 AM
"Call her and tell her."
 
@KajHansen So what does that mean?
Oh okay, it's cheating
 
mhmm
 
The guy was trying to make a joke, right @KajHansen?
 
Definitely
 
Since you haven't studied inverse limits, here's something that might surprise you : $Gal(\overline{\Bbb Q}/\Bbb Q)$ is the inverse limit of $Gal(L/K)$s, $L$ ranging over all finite extensions of $K$. The morphisms are restriction homomorphisms, but in that case you need to order the extensions of $K$ properly. That, I think, is done by use of the Krull topology which I haven't studied.
 
8:48 AM
"Restriction homomorphisms"?
 
I think I have to study infinite galois theory properly at some point in near future.
 
@KajHansen Thanks
 
@KajHansen $Gal(L'/K) \to Gal(L/K)$ where $L \subseteq L'$
 
Sure thing @Venus. I see @BalarkaSen
 
But to do that you need to "order the field extensions". For example, both $\Bbb Q(\sqrt{2})$ and $\Bbb Q(\sqrt{3})$ are extensions of $\Bbb Q$, but there is obviously no inclusion.
At least that's how I understand it.
 
8:51 AM
Yeah, that makes sense
 
If you study that stuff, @KajHansen, I'd be interested to discuss it with you. I know nothing about it, except that single fact.
 

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