Mathematics - 2014-09-04 (page 2 of 4)

4:18 PM

@Khallil Thanks for the compliment! blush

4:28 PM

I've got a quick question, @IceBoy. How do you add the 'Glider' text to your profile when I click on your image? I'd like to add mathlete to mine.

topper

Can anyone link me to an idiot-proof explanation of integration by substitution? Read several pages on it, still not really feeling it

I'll just try some worked examples.

Khallil

This seems like a fairly good link. I myself haven't seen it before, but it makes sense.

topper

Okay, just got one right!

Balarka Sen

Meh. The forum I am in is lacking interesting NT problems.

Nothing to do. Nothing to solve.

sigh

rehband

@BalarkaSen What forum are you in?

Jasper Loy

4:39 PM

There should be more simple questions here for me to answer.

Balarka Sen

@rehband Eh, an infamous one.

rehband

@BalarkaSen How about some limits/series? :D What's that forum called?

Balarka Sen

@rehband Don't care if it's not related to NT, unlike the last problem Chris'ssis gave me.

@rehband Math Help Boards.

rehband

@BalarkaSen :) What was the last problem that Chris gave you? Do you mean the one that had a recursive solution?

Balarka Sen

@rehband No, the double sum limit.

rehband

4:41 PM

@BalarkaSen Right

Ice Boy

@Khallil click on your image----->user profile------>about(edit)

Khallil

That's the ticket!

Thanks, @skull!

Clears throat I mean, @IceBoy.

^_^

Ice Boy

:D

Jasper Loy

There is ice boy and ice girl, where is ice baby?

Ice Boy

@JasperLoy here

Jasper Loy

4:47 PM

@IceBoy The two LaTeX guides I gave you are the two best free ones.

Ice Boy

@JasperLoy great!

topper

Not looking for a solution yet but what would your first step be to integrate $$\frac{x-1}{\sqrt{x}+1}$$ Clearly I have to sort out that nasty denominator.

Balarka Sen

$x - 1 = (\sqrt{x} + 1)(\sqrt{x} - 1)$

rehband

@BalarkaSen How about this one $$\lim_{n\to\infty} \frac{ \int_a^b f^{n+1}(x) dx }{ \int_a^b f^n(x) dx }$$ where $f:[a,b] \to [0,\infty)$ is continuous and $f\neq0$

Balarka Sen

Ba dum tss

@rehband Ughh.

Looks ugly.

rehband

4:50 PM

@BalarkaSen :D

topper

@BalarkaSen Damn interesting, using the difference of squares when there isn't an explicit square!

Ice Boy

4 hours ago, by Balarka Sen

@robjohn I'd have much preferred him to figure it out by himself. sigh

Jasper Loy

@topper Are you a math major?

Balarka Sen

@IceBoy Asked for the first step.

Not my fault if there is only one step needed!

Khallil

Is it equal to 1, @rehband?

(That was a total shot in the dark.)

rehband

4:52 PM

@Khallil I don't know yet :P

Balarka Sen

@IceBoy Whilst in there, he asked whether he should use L'Hopital.

Compare the questions, then quote.

Ice Boy

it doesn't matter

teach a man how to fish...

Balarka Sen

random trolling.

ignores @IceBoy

Ice Boy

np

...and he will never starve.

Jasper Loy

What should I change my username to?

Ice Boy

4:56 PM

give a man a fish and you feed him for a day; teach a man to fish and you feed him for a lifetime

== English == === Etymology === This saying was coined by Anne Isabella Thackeray Ritchie (1837–1919) in her novel, Mrs. Dymond (1885): "I don't suppose even Caron could tell you the difference between material and spiritual," said Max, shrugging his shoulders. "He certainly doesn't practise his precepts, but I suppose the Patron meant that if you give a man a fish he is hungry again in an hour. If you teach him to catch a fish you do him a good turn. But these very elementary principles are apt to clash with the leisure of the cultivated classes. Will Mr. Bagginal now produce his ticket...

Hippalectryon

Ice Maiden @JasperLoy :P

Balarka Sen

@rehband where did you get that problem?

rehband

@BalarkaSen It's problem 1.47 in Ovidiu Furdui's book.

Jasper Loy

I think I shan't change my username. That way, people can still recognise me.

Balarka Sen

and i presume $f^n(x)$ means $\left ( f(x) \right )^n$ and not $\left ( f \circ f \circ \cdots \circ f\right ) x$?

rehband

4:59 PM

@BalarkaSen You are correct

Ice Boy

too many teachers do not teach their students "how to fish"

Balarka Sen

Hello @Sawarnik

Sawarnik

Hello @Balarka That was fast :)

Balarka Sen

@Sawarnik Read lots of SH stories.

Sawarnik

:D

Like? :)

Balarka Sen

5:07 PM

Six Napoleons, for one.

Sawarnik

Nice.

Balarka Sen

Three students, Resident Patient, Thor Bridge.

Sawarnik

Thor Bridge ... :\

Balarka Sen

Crooked Man, Man with the twisted lip.

@Sawarnik The one in which the lady murdered herself on the bridge.

I know, I know.

Sawarnik

@BalarkaSen Yes, I remember :)

Balarka Sen

5:09 PM

It's from the casebook

Sawarnik

Have you read any bad stories, like the Creeping Man?

That one is especially disgusting.

Balarka Sen

Yup.

Indeed.

Three students was interesting however.

@Sawarnik Did I tell you about Man with the twisted Lip?

Sawarnik

Yup.

@BalarkaSen Indeed :D

I am coming to Kolkata btw for the first time, around 7 Nov :D @Balarka

Balarka Sen

@Sawarnik Bruce-Partington plans was the awesomest story ever.

@Sawarnik Oh!

How come?

Sawarnik

@BalarkaSen Yup.

@BalarkaSen RBI quiz regional rounds :| :|

Balarka Sen

5:14 PM

@Sawarnik wat?

PVAL

Ah, mathematics stack exchange. Closing and downvoting a question equivalent to this one mathoverflow.net/questions/78771/… . Only took about a minute. (The question on MO has 1 sketchy answer by an expert).

Sawarnik

@BalarkaSen This thing, rbi.org.in/commonman/english/Scripts/PressReleases.aspx?Id=1146 By some strange luck I passed the city rounds :|

Balarka Sen

Ah, OK. best of luck! where are you coming? exact location?

Sawarnik

@BalarkaSen Not sure.

But must be near the RBI office.

[Google says near GPO]

Balarka Sen

I see.

rehband

5:18 PM

Is there a downloadable version of the MSE editor?

Sawarnik

How far is Belur anyway? @Balarka

rehband

Or just a better way to write stuff down than in the 'Ask question' section and then screenshotting them :P

Balarka Sen

@Sawarnik Not very far. But I don't live in Belur =P

Sawarnik

@BalarkaSen :O :O Then where?

Balarka Sen

Actually, RBI office is close to where my father's workplace is. When will your quiz would be held?

@Sawarnik Someplace you never even heard of.

Sawarnik

5:22 PM

@BalarkaSen 7 Nov, I think.

Balarka Sen

I mean the time.

Sawarnik

@BalarkaSen I know, but we have Google. :P

@BalarkaSen No idea.

Balarka Sen

@Sawarnik Hmm. Oh well. I presume you will make a night's stay?

Sawarnik

Yup.

Balarka Sen

@Sawarnik Sodepur, Panihati.

Sawarnik

5:24 PM

But with accompanying teachers :(

Balarka Sen

haha OK. I guess we can't meet, but at least I'd know you are in Calc. Have fun!

Sawarnik

I know :D

@BalarkaSen I am a bit afraid :|

Balarka Sen

why?

Sawarnik

New place. Plus first time travelling without parents :| (but teachers :( )

Balarka Sen

It'd be fine.

Sawarnik

5:29 PM

Ok.

Hippalectryon

@Sawarnik Time travelling ? Interesting

Jasper Loy

It seems that my enemy on Math SE has stopped making stupid comments all over the place. Well done!

Ice Boy

don't let your guard down

Jasper Loy

5:53 PM

I suspect some mod told her to stop making silly comments.

Chris's sis

Maybe some are interested to answer this question, it's interesting - math.stackexchange.com/questions/919572/…

topper

@JasperLoy Sorry for late answer - I'm not, I'd be ashamed with these questions if I was. I have a first degree in computer science from around 15 years ago, and I'm about to do a second degree in business. Despite me getting 740 in GMAT, I'm forced to do "prerequisite" courses in maths, statistics, and economics, just to be allowed to take certain courses within the degree itself

Khallil

I totally agree with that statement, @IceBoy.

51 mins ago, by Ice Boy

too many teachers do not teach their students "how to fish"

rehband

@BalarkaSen The author has a beautiful solution to the problem I sent you earlier. I have written it down in my own words to memorise the strategies he used

Ice Boy

@Khallil sad, but true

rehband

5:56 PM

@BalarkaSen i.imgur.com/HMv41YF.png in case you care :D

Chris's sis

For some reason I won't share it know, my question there is pretty important!

Jasper Loy

@V-Moy I look at your profile and I do not see any serial downvotes.

V-Moy

Yuhuu!

Jasper Loy

@Chris'ssis It must be related to a secret problem you are working on, maybe RH!

Hippalectryon

@BalarkaSen teach me phishing :D

V-Moy

5:58 PM

@JasperLoy It was.

Chris's sis

@JasperLoy :-)

Jasper Loy

@V-Moy Sorry, what was what?

Khallil

Does anyone here hate math?

V-Moy

BTW, I want to ask something that's why I log in to chat room. Does anyone here know who is user: Marvis? He is very good at calculus but his account is not active anymore.

Jasper Loy

@V-Moy He deleted his account.

@V-Moy I also deleted my account about ten times.

V-Moy

6:01 PM

@JasperLoy Why he delete his account?

Jasper Loy

@V-Moy Only he will know.

V-Moy

@JasperLoy Do you know who is he? A Prof or PhD student?

Jasper Loy

@V-Moy I don't know. And Marvis is a toothpaste brand.

V-Moy

@JasperLoy Apparently, you're a new user here. Nice joke!

Jasper Loy

@V-Moy I am not a new user. I told you I deleted my account about 10 times.

V-Moy

6:04 PM

@Chris'ssis ??

Daniel Fischer

@V-Moy It's Jasper's ten-thousandth account, approximately.

Jasper Loy

@V-Moy Also, that was not a joke. Marvis is really a toothpaste brand.

Daniel Fischer

He always deletes his accounts and creates new ones a few days later.

Chris's sis

@V-Moy Yes?

V-Moy

@Chris'ssis You know who is Marvis?

Ice Boy

6:05 PM

we use "over 9,000" on the internet @DanielFischer

Chris's sis

@V-Moy Yeah, not personally, but there was such a user here. Why do you ask me that?

Daniel Fischer

@IceBoy But if I had written that, somebody would have starred it.

Ice Boy

@DanielFischer you are soooo low profiled pal

V-Moy

@JasperLoy Why do you delete your account 10x?

Jasper Loy

@V-Moy It is a LONG story, lol. So I rather not say.

V-Moy

6:07 PM

@JasperLoy You can ask question and award a super big bounty. LOL

Jasper Loy

@V-Moy So you are still in school? Are you going to study math in college?

V-Moy

@Chris'ssis I ask you because I think you have interacted with him many times in the past

Chris's sis

@V-Moy He answered some of my questions in the past. He's a very clever person, gave many good answers, but I think he deleted his account for some months. Btw, are you Marvis? :-)

V-Moy

@JasperLoy Yup! I don't know yet. It's still 4 years from now

Jasper Loy

@V-Moy What does V-Moy mean? Is it your name?

V-Moy

6:11 PM

@Chris'ssis Do you mean if we delete our account and then we can re-activate again? If so, how about the rep and badge?

@JasperLoy V for Valentina, not Vendetta. :D

Jasper Loy

@V-Moy I have never heard of Moy as a name.

@V-Moy If we delete account, points are gone forever. Your posts remain.

Chris's sis

@V-Moy Ask @robjohn about that, I'm not very interested in rep and badge, he must know these details far better than me.

V-Moy

@Chris'ssis Of course not! Are you a woman?

Jasper Loy

@Chris'ssis I know better than him, lol.

@V-Moy Yes.

Chris's sis

@JasperLoy lollllllllll :-)))))))))))))) That was a good one!

Jasper Loy

6:14 PM

@Chris'ssis Why do you lol? You mean you are not a woman?

V-Moy

@JasperLoy It's a Chinese name.

Jasper Loy

@V-Moy OK. I now suspect you are from HK, lol.

V-Moy

Yuhuu Mr. @robjohn!

@Chris'ssis Are you really a woman?

Jasper Loy

@V-Moy Yes.

V-Moy

@JasperLoy No, you're wrong. I'm not from HK

robjohn

6:16 PM

@V-Moy yes?

V-Moy

@JasperLoy Really? I thought the women around here only me and Ms. AmWhy

@robjohn Do you know who is Marvis?

Jasper Loy

@V-Moy There are many women on this site. And amWhy is an old woman.

robjohn

@V-Moy I remember he used to be here, but then he left.

V-Moy

@JasperLoy Never say OLD to woman!

Jasper Loy

@V-Moy Nothing wrong with being old. However, most people become more stupid as they grow older.

V-Moy

6:20 PM

@robjohn if I may know, why he left?

Jasper Loy

@V-Moy Nobody knows.

V-Moy

@JasperLoy I thought Mr. @robjohn know since he is a moderator

Jasper Loy

@V-Moy Even if he knows, he can't tell you, because mods are sworn to secrecy.

V-Moy

@JasperLoy I've never said wrong being old

Jasper Loy

@V-Moy I never said you said so.

robjohn

6:22 PM

@V-Moy It appears that he got some downvotes and started posting discontented messages.

Jasper Loy

That is what I suspect too, but only he would know for sure.

Hippalectryon

Al long as there's not wut women it's ok ...

V-Moy

Ohh! Downvoters, I hate them so much specially to those who downvote without saying a word.

Jasper Loy

Yes, very often the downvotes are wrong because the answers are right.

However, most users here are rather stupid.

topper

:D

waves

Although sometimes I don't confuse plus and minus.

Jasper Loy

6:25 PM

I am now talking a bit like Jonas, lol. I love Jonas Teuwen!

V-Moy

Even there's a user who brag about his many downvotes he did. Silly!

the push ups guy ?

or was it sit ups?

I can't remember

chin ups

6:28 PM

@JasperLoy Luckily, most of user here treat me well. So that's why my parents let me stay online till late without being worried

Ice Boy

Orly?

}:-)

V-Moy

@IceBoy @Hippalectryon No comment! I don't want to make him angry and then he starts downvote my answers & questions.

Ice Boy

@V-Moy never worry about stuff like that...life is too short

Jasper Loy

@V-Moy I see that you are very interested in integrals, lol. I hate them.

V-Moy

@IceBoy But it'll ruin my mood all day!

Ice Boy

6:33 PM

@V-Moy don't let it, save your energy for what matters

Jasper Loy

@V-Moy Never let anyone online ruin your mood.

V-Moy

@JasperLoy I love calculus!

Jasper Loy

@V-Moy Where do you study calculus from?

V-Moy

@JasperLoy Yeah, it's easy to say like that

Jasper Loy

@V-Moy Anyway, where are you from, if it is not a secret?

Trevör Anne Denise

6:35 PM

Hey guys, I'm coming with a problem that I have in maths !

Mike Miller

@V-Moy It won't ruin your day. That user's modus operandi is to downvote closed questions so that they're deleted. That user doesn't downvote people because he/she is angry at them.

Trevör Anne Denise

(not very surprising on a math forum though...)

Ice Boy

askaway

V-Moy

@JasperLoy autodidact. Sometime my brother if my mom insist him

Trevör Anne Denise

Well, I have a problem to explain a result

V-Moy

6:36 PM

@JasperLoy One of the countries in Asia

Hahaha

Parth Kohli

@JasperLoy Hello.

Jasper Loy

@V-Moy You spell mum as mom, so you use American English lol.

@ParthKohli Hi!

Trevör Anne Denise

I have a geometric sequence

That is related to another squence

(

It is vn = un + 400

vn is geometric

V-Moy

@MikeMiller But it almost always ruins my day in school

Trevör Anne Denise

To find a certain term of my sequence

I used "the formula that we all know"

Since vn = un + 400

Mike Miller

6:38 PM

@V-Moy I'm just saying that particular user isn't anything to worry about - not that there aren't some people out there who downvote hostilely.

But you should work to not let it bother you! Life is full of challenges etc.

Trevör Anne Denise

To find un with vn, I use my formula to find a specific term of vn and then a subtract 400 from that

V-Moy

@JasperLoy Hollywood movie effect

Jasper Loy

@MikeMiller Ultimately votes here should not be worried about.

Trevör Anne Denise

Now the problem is that I want to find the sum of un

So I used a formula to find the sum of vn

Jasper Loy

OK, and then?

Trevör Anne Denise

6:40 PM

and then, intuitively, I understood that un was equal to the sum of vn - (400 * numbers of terms)

It seems obvious to me

but I don't know how to justify that

V-Moy

@MikeMiller I'll try that. It's easy to handle my emotion being a teenager

Jasper Loy

@TrevörAnneDenise It is obvious.

Trevör Anne Denise

So will my math teacher accept it without justification ?

Jasper Loy

@TrevörAnneDenise Yes, and you should think about why it is true though.

@V-Moy My favourite movie is Good Will Hunting.

Trevör Anne Denise

Hum....

@JasperLoy Well, it's so obvious that I am having difficulties to understand why ^^

V-Moy

6:43 PM

@JasperLoy That's an old movie. Robbin Williams got an Oscar in that movie.

Jasper Loy

@V-Moy Yes, I watched it about 10 times. I also like A Beautiful Mind.

V-Moy

@JasperLoy But Matt Damon is cute when he was a young lol

Jasper Loy

@V-Moy Yes, he is hot, like me, lol.

@ParthKohli How are your studies?

V-Moy

I prefer Twilight tetralogy

Jasper Loy

Taylor Lautner is hot too.

V-Moy

6:45 PM

@JasperLoy How old are you?

Jasper Loy

@V-Moy Too old for you.

Hippalectryon

What is this, a math chat ? ლ(ಠ益ಠლ)

Jasper Loy

@V-Moy I only watched the first 3 out of 5.

V-Moy

@JasperLoy Yup! He is damn hot hahaha

Jasper Loy

@V-Moy I am also from a country in Asia, lol.

V-Moy

6:47 PM

I watched all of them

Where?

I bet India!

Jasper Loy

Why India? Is my name Indian? lol

V-Moy

Your name like Twilight character

Jasper Loy

I am not Ramanujan. Ethan on this site is Ramanujan incarnate.

Khallil

Ethan?

V-Moy

Cleo!

Jasper Loy

6:49 PM

Yes, the great Ethan.

Khallil

Ethan the great?

Jasper Loy

I am only a banana.

2

Hippalectryon

@JasperLoy May I eat you ?

Jasper Loy

Yes?

Yes, you may eat me.

V-Moy

@JasperLoy You didn't answer my question. How old are you and where are you from?

Jasper Loy

6:51 PM

@V-Moy I am 33, lol.

Hippalectryon

٩(⁎❛ᴗ❛⁎)۶

Khallil

Before any cannibalism occurs, have a listen to this song.

Jasper Loy

Once you are past 30, you are OLD.

V-Moy

Really? I thought you're a college boy

Jasper Loy

@V-Moy No. You tell me where you are from first.

Hippalectryon

6:52 PM

Once you are past 20 you are old

V-Moy

So, where are you from? SG?

Jasper Loy

@V-Moy You tell me first, lol.

Hippalectryon

SG ?????

South Germany ? :P

V-Moy

The old one should be the first

@Hippalectryon Singapore

Hippalectryon

Oh

Jasper Loy

6:53 PM

@V-Moy Haha, I am from SG, but there are at least two people there with my name.

V-Moy

If Germany, it should be east and west

Jasper Loy

@V-Moy So where are you from?

V-Moy

@JasperLoy I don't believe you, although SG is small, no way there are only two Jasper

Hippalectryon

All is normal Sir ... V

Jasper Loy

@V-Moy I did not say there are only two, I said at least two, LOL

V-Moy

6:56 PM

I am near your country

Jasper Loy

@V-Moy OK, Malaysia?

Hippalectryon

@JasperLoy He means Mars

Jasper Loy

@Hippalectryon How did that happen?

Hippalectryon

@JasperLoy Magic :D

Huy

@Hippalectryon I am old? ._____________________.'

Nick

6:57 PM

@Hippalectryon: There's no such thing as magic, only withheld information.

V-Moy

@JasperLoy I think that's enough info I gave you. Remember, secret make a woman be a woman (>‿◠)

@Huy

@Nick

@Nick Shhhh dun tell i'm with da KGB

Jasper Loy

6:58 PM

@V-Moy Erm, OK.

Hippalectryon

@JasperLoy Notice your pseudo on that second pic :c sorry

Jasper Loy

@Hippalectryon LOL

Nick

Guys, in $\LaTeX$, what's the font used for matrix variables?

Transcript for

$Mathematics$ Mathematics