The Easiest Integral on YouTube

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  • Опубликовано: 21 ноя 2024

Комментарии • 1,3 тыс.

  • @blackpenredpen
    @blackpenredpen  5 лет назад +637

    OK, I checked the answer and it was correct! ruclips.net/video/mUXdgY5MeEg/видео.html
    Happy New Year!!!

    • @notnilc2107
      @notnilc2107 5 лет назад +8

      I approve.

    • @alexsanders7303
      @alexsanders7303 5 лет назад +2

      Lol, just finished the vid and relaised this

    • @marziyaali7962
      @marziyaali7962 5 лет назад +1

      Oh god my maths test is on 1st Aug and I haven't prepared for it yet...... integrals is also in test!😢😢😢

    • @pongwang9893
      @pongwang9893 5 лет назад +1

      thanks , the integral is really amazing. so intelligent.
      Mathematics is deeply bottomless, and probability and statistics are more difficult to understand.
      Gamma distribution, chi-square distribution, is so hard to understand.

    • @sahlileila6382
      @sahlileila6382 5 лет назад

      i really need your help to intigrate this for me i really need it ----- x-1*sqrt.2x-x*2
      /x+1

  • @wellbangok8959
    @wellbangok8959 7 лет назад +4930

    Somewhere out there, a professor is gonna watch this video and make this problem a test question. RIP.

    • @davidkippy101
      @davidkippy101 7 лет назад +152

      Sheev Palpatine Saw the comment, liked for the name

    • @blackpenredpen
      @blackpenredpen  7 лет назад +487

      Sheev Palpatine I just had to pin this comment.

    • @levi4328
      @levi4328 7 лет назад +147

      oh no, don't give them ideas

    • @Mathemusician97
      @Mathemusician97 7 лет назад +105

      Sheev Palpatine that would be acceptable if that was an extra credit question where if you get it right you get full credit for the exam

    • @神-w1y
      @神-w1y 7 лет назад +29

      Sheev Palpatine did you ever hear the tragedy of darth plagueis the wise?

  • @AviMehra
    @AviMehra 7 лет назад +2218

    Check the answer by differentiation

  • @BT7M
    @BT7M 7 лет назад +2765

    You know it's a hard problem when he has to use 3 colors

    • @blackpenredpen
      @blackpenredpen  7 лет назад +198

      BT7M yup

    • @isaacormesher2851
      @isaacormesher2851 7 лет назад +204

      blackpenredpenbluepen

    • @Anonymous_Poetry
      @Anonymous_Poetry 4 года назад +28

      This is not hard prblm we indians take 30 sec to solve this

    • @booga9584
      @booga9584 4 года назад +2

      @@g.peloni3694 none cause we never and then we're like wtf are we doing.

    • @midhun.m4963
      @midhun.m4963 4 года назад +1

      @@g.peloni3694 uff...😂I'm also An Indian I'm a Calculus Lover too...

  • @yoavcarmel1245
    @yoavcarmel1245 7 лет назад +505

    8:15 *erases that additional line*
    ohh god thank youu

  • @friendofjim
    @friendofjim 7 лет назад +949

    I don't want you to check your answer by differentiation. I want you to integrate your answer :D

  • @rileywells3045
    @rileywells3045 7 лет назад +340

    This is probably the most fun I've ever had watching a video about integrals! It was a long journey, but it was worth every second. Thankyou for such a great video!

    • @blackpenredpen
      @blackpenredpen  7 лет назад +19

      Riley Wells my pleasure!!!!

    • @leif1075
      @leif1075 Год назад

      @@blackpenredpen But why on earth would you do that second substitution at all? Isn't there another way maybe more intuitive..like integration by parts Ibwas thinking..Hope you can respond when you can.

  • @flansterr
    @flansterr 7 лет назад +510

    I think you did a step wrong somewhere, please differentiate it to check.

  • @natalieeuley1734
    @natalieeuley1734 7 лет назад +98

    I love this. Great example of when to actually use partial fractions, too. I'm adding this channel to my list of favorite math channels! 🤓🤓🤓

  • @davidkippy101
    @davidkippy101 7 лет назад +541

    You're going from blackpenredpen to 3blue1brown

    • @blackpenredpen
      @blackpenredpen  7 лет назад +178

      How so? His vids are way cooler

    • @Number3pt14
      @Number3pt14 7 лет назад +75

      Because this is really REALLY complicated yet you manage to explain it so well. Its cool at the same time

    • @davidkippy101
      @davidkippy101 7 лет назад +52

      blackpenredpen Because of the color markers you are using

    • @blackpenredpen
      @blackpenredpen  7 лет назад +95

      blackpenredpen and sometimes blue : )

    • @NoNameAtAll2
      @NoNameAtAll2 7 лет назад +29

      blackpenredpenbluepengreenpen

  • @andresvivas2814
    @andresvivas2814 7 лет назад +788

    when you say "please do not ask me to check the answer by diferentiation", I'm pretty sure you were really thinking "please ask me to check the answer by diferentiation" ... So, in order to please you..... Would you check the answer by diferentiation???? Please :)

    • @blackpenredpen
      @blackpenredpen  7 лет назад +180

      lol! I am waiting for some viewers to do it!

    • @manuelbonet
      @manuelbonet 7 лет назад +48

      blackpenredpen We want you to check it by differentiation. It's always easier than the integration, right?

    • @monzur1947
      @monzur1947 7 лет назад +28

      blackpenredpen I proved it using my calculator. Is that good enough?

    • @aysikl
      @aysikl 7 лет назад +10

      scrolled down expecting the comment "check the answer by differentiation" as top or only comment ..
      urs was 3rd and has a bunch of text around it
      internet, you disappoint......
      (altho the expectation ur not meeting, is actually... so in a way.... yay! ....)

    • @blackpenredpen
      @blackpenredpen  7 лет назад +23

      Maybe?!

  • @maxhaibara8828
    @maxhaibara8828 7 лет назад +568

    I have a challenge for you. Make the generalization of the integral of n-th root of tan x dx

    • @kamarinelson
      @kamarinelson 6 лет назад +50

      I was wondering this myself lol at the beginning of this video. I'm betting it inevitably leads to just letting u= the n-th root of tan(x) and then integrating the resulting rational function using partial fraction decomposition - maybe synthetic division for powers of tangent not = 1 or 2.

    • @kamarinelson
      @kamarinelson 6 лет назад +21

      of course, I'm ignoring any possible trig manipulations ...

    • @eroskuikel9688
      @eroskuikel9688 6 лет назад +16

      This should be easy. Separate tan^n into tan^(n-2) and tan^2 then integrate by parts. Then substitute sec^2-1 for tan^2 and you get a reduction formula. Evaluate integral of tan^2 and that should be enough I guess.(I havent tried this but I think this works for even exponents only.)

    • @eroskuikel9688
      @eroskuikel9688 6 лет назад +2

      Kyro well Oh yeah..

    • @surenmoodley7744
      @surenmoodley7744 3 года назад +3

      Lol that's sadistic!

  • @bonbonpony
    @bonbonpony 7 лет назад +43

    16:56 Yeah, putting down some TNT on that would definitely help :)
    18:18 It's quite interesting that `1/2` and `√3/2` appear in the completed square, because:
    a) they are the real and imaginary part of the cube root of `-1` that appear in the complex factorization of the denominator;
    b) they are the sine and cosine of the 60° angle at which this cube root lays with respect to the real axis :)
    c) we've got the cube root (of the tangent) in the original integrand.
    21:30 We have to go deeper... :>
    23:52 The dream is collapsing :J

    • @blackpenredpen
      @blackpenredpen  7 лет назад +7

      Ah!!! I like the pt u made at 18:18... and what u said "The dream is collapsing"

  • @shakirahsanromeo7863
    @shakirahsanromeo7863 7 лет назад +408

    I fear you may run out of substitute variables one day :P

    • @blackpenredpen
      @blackpenredpen  7 лет назад +84

      Shakir Ahsan Romeo probably. Next I will use alpha, beta

    • @iconoptixx
      @iconoptixx 6 лет назад +71

      *creates new alphabet after using all latin, greek, cyrillic, hebrew and arabic letters*

    • @Queenhideyxo
      @Queenhideyxo 6 лет назад +11

      Evolution can you give me more letters for my substitions into different integral worlds?
      Sure blackpenredpen
      ACTUALLY USES OLD LETTERS FOR SUBSTITUTIONS LIKE A BOSS

    • @arnavanand8037
      @arnavanand8037 5 лет назад +12

      After that start using ♤♡◇♧¤▪☆

    • @hamiltonianpathondodecahed5236
      @hamiltonianpathondodecahed5236 4 года назад +7

      How about हिन्दी

  • @tipoima
    @tipoima 7 лет назад +38

    30:40 "Please, do not ask me to check the answer by differentiation"
    Hey, you should totally check the answer by differentiation!

  • @azmath2059
    @azmath2059 7 лет назад +11

    Now that is just incredible! By far one of the most difficult integrals I have ever seen and you have solved it so elegantly and so well.

  • @ianbo1
    @ianbo1 7 лет назад +111

    Worth every second of the watch. Thank you!

  • @particleonazock2246
    @particleonazock2246 4 года назад +38

    This problem was soooooo easy! I solved it when I was a foetus. Hats off to this young gentleman realising the foetal power of solving integrals!

    • @lih3391
      @lih3391 2 года назад +3

      Fetus?

    • @JMZReview
      @JMZReview Год назад +4

      Bro really spelled it with an o 💀

    • @General12th
      @General12th Год назад

      @@JMZReview diarrhoea

  • @mr.gentlezombie8709
    @mr.gentlezombie8709 7 лет назад +91

    Now do the integral of (tanx+(tanx)^(1/2)+(tanx)^(1/3)+(tanx)^(1/4)+(tanx)^(1/5)...)

  • @malayagr
    @malayagr 2 года назад +8

    The second integral can be done without any substitution:
    Multiply and divide by 2 (you can factor out the divide by 2 later, with the final constant distribution):
    (2t+2)/(t²-t+1)
    The derivative of the denominator is 2t-1. So, write the integral as:
    (2t-1+3)/(t²-t+1)
    Split the fraction:
    (2t-1)/(t²-t+1) + 3/(t²-t+1)
    The first one's integral is ln|t²-t+1|. For the second one, complete the square as (t-1/2)²+(√3/2)². The integral is 2√3*invtan((2t-1)/√3).
    Now, distribute the divide by 2:
    1/2*ln|t²-t+1|+√3*invtan((2t-1)/√3).

  • @JoJoJet100
    @JoJoJet100 6 лет назад +30

    Doctor: You have 31 minutes and eight seconds to live.
    Me: immediately opens this video

  • @ATeamBrown
    @ATeamBrown 7 лет назад +8

    This couldn't have been uploaded at any time better, I'm just about to fall asleep and I always trance at your videos which makes me go to sleep! Thank you so much! :D

  • @mathematically4761
    @mathematically4761 2 года назад +9

    I thought he will forget the + C part
    Truly professional to the core
    I am starting to fall in love with math and pens
    And of course our one and only
    *CALCULUS*🥳🥳

  • @Kreighzey
    @Kreighzey 7 лет назад +44

    30:40 differentiASIAN

  • @sethleverett8889
    @sethleverett8889 3 года назад +29

    Video: “Easiest integral on RUclips”
    Me: oh that’s nice let’s check it out
    Also video: equation is written very small and 31 minutes
    Me: oh no...

  • @loganmancuso3791
    @loganmancuso3791 7 лет назад +151

    Ok to the one dislike on the video I want you to post a follow up showing everyone how you do this integral.

  • @12345678910111213796
    @12345678910111213796 7 лет назад +140

    Can you check the answer by differentiation ?

    • @blackpenredpen
      @blackpenredpen  6 лет назад +19

      Pedro Bessa maybe one day :)

    • @nationalstudyacademykim5030
      @nationalstudyacademykim5030 5 лет назад +1

      Really quick way to check. Takes 30 seconds. Plug in some values the the limit of integration and use fund. Thm of calc p2.

  • @Xperia347
    @Xperia347 7 лет назад +114

    Could you check the answer by differentiation?

  • @stanschimerman
    @stanschimerman 6 лет назад +7

    Fantastic job of explaining every step!

  • @andrecouverette
    @andrecouverette 2 года назад

    Best problem ever!
    Tour de force for methods of integration.
    I counted eight different tricks.
    TI-84 plus showed it correct over:
    -2π

  • @rohitg1529
    @rohitg1529 7 лет назад +19

    Please differentiate this to get back to cuberoot of tan x

  • @dovidglass5445
    @dovidglass5445 3 года назад +1

    I love how enthusiastic you are! What great videos you make.

  • @eveliohernandez6595
    @eveliohernandez6595 7 лет назад +5

    i never´ ve seen a intgral like this
    . i been watching all your videos and in my opinion is very useful. in other side i want to thank, you videos are helping me to improve my english how you know ,y native language is spanish, but thanks for share it. congrats

    • @blackpenredpen
      @blackpenredpen  7 лет назад

      Thank you so much. I am very happy to hear your nice comment! Keep up the good work too!

  • @DavideCosmaro
    @DavideCosmaro 10 месяцев назад +1

    25:49 let's all appreciate how his only mistake in the video was using the wrong coloured marker

  • @X-3K
    @X-3K 7 лет назад +348

    what about the tan(x) root of tan(x)?

    • @nestorv7627
      @nestorv7627 7 лет назад +42

      I think impossible

    • @aceeternus4027
      @aceeternus4027 7 лет назад +24

      NestorV S I thought you could integrate anything you wanted

    • @RubALamp
      @RubALamp 7 лет назад +96

      Ace Eternus no, there are functions that their integral have no solution. A classic example of this is the function f(x)=e^x^2.

    • @mh-no5it
      @mh-no5it 7 лет назад +59

      Ace Eternus
      Some functions have no elementary anti derivative take x^x for example, you have to settle for a series.

    • @sinistrolerta
      @sinistrolerta 7 лет назад +43

      Gregory House Tecnically there is a solution, but it just can't be expressed in terms of exponentials, polynomials, logarithms etc

  • @calyodelphi124
    @calyodelphi124 5 лет назад +1

    This is way late, but you can further compactify the answer (and show off some extra algebra skills) by taking advantage of log properties like so:
    1/2ln[ sqrt( tan^4/3 x - tan^2/3 x + 1 ) / ( tan^2/3 x + 1 ) ] + sqrt(3) arctan( (2 tan^2/3 x - 1)/sqrt(3) ) + C.

  • @tavishu
    @tavishu 4 года назад +3

    Great, now integrate (tanx)^1/5

  • @meraldlag4336
    @meraldlag4336 Год назад

    I'm so happy to see a "BIG INTEGRALS NO SHORTCUTS" playlist, will watch them all

  • @void2509
    @void2509 4 года назад +45

    Imagine doing a test and solving this problem. You did every step right, but you forgot to write plus C

    • @delta2884
      @delta2884 3 года назад +8

      And professor deducts 1mark for that

    • @invasion8318
      @invasion8318 3 года назад +6

      @@delta2884 my professor would tear the whole thing and give you 0 ;)

    • @dzlcrd9519
      @dzlcrd9519 3 года назад +1

      Easier when in France they ask for a antiderivative so you don't have to add +C

    • @好吧-h6k
      @好吧-h6k 3 года назад

      Calc II + Calc II

  • @howtoglobal7901
    @howtoglobal7901 4 года назад +1

    i just love your videos man... i just want to say that you helped me overcome my fear of integrals.. and your approach to not just this video but all the others are just brilliant.. thank you.

  • @BlackFiresong
    @BlackFiresong 7 лет назад +3

    I kept on making mistakes when trying to check this answer by differentiation, and had pledged to keep this video tab open until I had successfully checked it. So pleased to say that I finally got it right today! I can close the tab now. :D

    • @blackpenredpen
      @blackpenredpen  7 лет назад +1

      BlackFiresong wow nice!!! I will check it one day too.

    • @BlackFiresong
      @BlackFiresong 7 лет назад +1

      Thank you so much for replying! Love your work. :) Please do keep the crazy challenges coming. You have really helped to rekindle my love of Maths!

    • @blackpenredpen
      @blackpenredpen  7 лет назад +1

      BlackFiresong I am very glad as well!! Thank you for watching my videos :)

  • @hendrickdias8366
    @hendrickdias8366 7 лет назад +1

    Watching this made me very relaxed. You sir deserve a subscribed!

  • @vj_henke
    @vj_henke 7 лет назад +37

    This channel is now offically a MATH MEME !
    "How about the integral of [fancy variation of sqrt(tan x)] ?" - bprp, you have a long meme carrier ahead...

    • @blackpenredpen
      @blackpenredpen  7 лет назад +11

      oscarjd74 OH WOW!!!! YOU ACTUALLY DID IT!

    • @vj_henke
      @vj_henke 7 лет назад +3

      NEAT, instant screen saver ^^

    • @caducoelho2221
      @caducoelho2221 7 лет назад +1

      How cool iz dat?! HAHAHAH

  • @enriquevanegas5741
    @enriquevanegas5741 5 лет назад

    Jesus Christ! With this you have won a new follower! Subscribed!

  • @bonbonpony
    @bonbonpony 7 лет назад +9

    Can you make some videos about the strategies of choosing the right integration technique for different problems?

  • @prollysine
    @prollysine 3 года назад

    Gratulálok, ez a szinte végig helyettesítéses módszer bemutatta, hol kezdődik az elméleti matematika !

  • @AviNash6817
    @AviNash6817 7 лет назад +7

    Good. this is a high level problem in my sheet .

  • @mutenfuyael3461
    @mutenfuyael3461 Год назад +1

    For B in 11:45, I like to multiplie by t in both side, and by going in the limit in +infini, we have 0=A+B

  • @DreamzAnimation
    @DreamzAnimation 7 лет назад +13

    please check the answer by differentiation

  • @chessandmathguy
    @chessandmathguy 7 лет назад +1

    very very good video and very satisfying to have a clean solution in the end.

  • @ulilulable
    @ulilulable 7 лет назад +3

    This is so great! I wish I still had the "mathematical muscle" to do this myself. Maybe one of these days...

    • @thelegendofme7520
      @thelegendofme7520 3 года назад +2

      Hey man just checking in, its been 4 years hows that math muscle working out for you? I challenge you to do 3 integrals! You can do it

    • @ulilulable
      @ulilulable 3 года назад

      @@thelegendofme7520 Aaany day now... ;)

  • @vynderma
    @vynderma 4 года назад

    Glad you enjoyed yourself with that. This is a great review of a lot of techniques.

  • @jeffreycanfield1939
    @jeffreycanfield1939 7 лет назад +44

    I'm worried for you.

    • @blackpenredpen
      @blackpenredpen  7 лет назад +71

      MistaTwoJeffreyTwenty Yaay
      U should worry about my students

    • @jeffreycanfield1939
      @jeffreycanfield1939 7 лет назад +8

      blackpenredpen oh noooo, show them sympathy please, they don't deserve this!

    • @blackpenredpen
      @blackpenredpen  7 лет назад +2

      Lol! I am teaching a calc2 class in the fall. We will see!! : )

    • @JorgetePanete
      @JorgetePanete 7 лет назад

      blackpenredpen the next year i will see integrals on our tests and i need a bless from Pitagoras to pass these exams

    • @Metalhammer1993
      @Metalhammer1993 7 лет назад

      if they´re not nice they get this integral on their exam! how about that? or worse sin(x)/x from 0 to infinity (but don´t ask for the steps. that´s overkill. though maybe you can show us that one? i didn´t see a single video on YT about that ntegral i would have understood. and the only idea to even make this possible would be using the mclaurin series of the sine)

  • @MRBYRNO2505
    @MRBYRNO2505 5 лет назад +1

    you are such an amazing teacher you make this advanced stuff seem so easy

  • @sirfactor
    @sirfactor 7 лет назад +5

    You earned yourself a new sub
    Thanks sir .

  • @tomhimler8175
    @tomhimler8175 7 лет назад +2

    You know what you have to do now? Now you have to do the integral of (tanhx)^(1/3). These videos are the best please keep posting them!

    • @blackpenredpen
      @blackpenredpen  7 лет назад

      Tom Himler Edward can help me with that. :)

    • @lezhilo772
      @lezhilo772 7 лет назад

      Just substitute the i's in the right places! tan(x) = -i tanh (ix), so you get tanh(x)=i tanh(-ix). Substitute this into the original integrand you get the cube root of i which is exp(i*pi/6), then you get an i outside when you replace dx with d(-ix). So the answer to integrating cube root of tanhx is just the original answer with all the x's replaced by -ix's, and an extra factor of exp(i*pi*2/3). Somehow you should be able to simplify everything in the end expression to show that the thing is real XD

  • @JBaker452
    @JBaker452 7 лет назад +9

    This does turn out to be a monster of an integral "doesn't it" :-)

    • @blackpenredpen
      @blackpenredpen  7 лет назад +2

      Yea, isn't it?!

    • @JBaker452
      @JBaker452 7 лет назад

      So how does the monster grow in the complex domain?
      I would love to see the secrets in there so that I might apply them to quantum mechanics (and my cool design for a new warp drive model).

  • @NWSCS
    @NWSCS 7 лет назад +1

    The interesting thing would be a professor taking the solution of that integral and making the class find the derivative maybe as a bonus problem on an exam.

  • @philmertens2673
    @philmertens2673 7 лет назад +44

    Please make a video about the nth root of tanx

    • @TheTimeDilater
      @TheTimeDilater 7 лет назад +5

      yes i agree

    • @dicandeo9698
      @dicandeo9698 7 лет назад +3

      Yes, that'd be great! :)

    • @sunriselp849
      @sunriselp849 7 лет назад +5

      I want to see that too

    • @jiaming5269
      @jiaming5269 7 лет назад +4

      tan(nx) ^ (1/n)

    • @angelmendez-rivera351
      @angelmendez-rivera351 7 лет назад +1

      I want to see this too, although I'll try it myself first because it may be possible that it be not expressible in terms of elementary functions or with a finite definite expression.

  • @Harothir
    @Harothir 7 лет назад +1

    This is just what I needed for my summer.

  • @benjaminbrady2385
    @benjaminbrady2385 7 лет назад +4

    I was kind of hoping to see you dancing in celebration chanting "One Take!" at the end

    • @xamzx9281
      @xamzx9281 7 лет назад +1

      who knows maybe its 10th take

    • @blackpenredpen
      @blackpenredpen  7 лет назад +1

      Notice that I didn't edit this video!

    • @markzero8291
      @markzero8291 7 лет назад +1

      MrQuantum "one take" and "1st take" are different.

    • @blackpenredpen
      @blackpenredpen  7 лет назад +4

      Mark Zero true. One take for this tho. I think it was my 3rd take bc my intros weren't good enough.

    • @xamzx9281
      @xamzx9281 7 лет назад +1

      Mark Zero k

  • @klokcotizao224433199
    @klokcotizao224433199 4 года назад +2

    And my professor is expecting me to solve that in only 10 minutes.

  • @sunglow9835
    @sunglow9835 5 лет назад +5

  • @nickriat7005
    @nickriat7005 7 лет назад +1

    If every question on the test is like this Mr. Chow, I might have to clear my whole weekend to complete it.

  • @clementtan5004
    @clementtan5004 7 лет назад +112

    here i am watching 30 minutes of math porn and not knowing wtf is going on

    • @kibayuuto6634
      @kibayuuto6634 6 лет назад +17

      Clement Tan isn’t that the case when watching regular porn too?

    • @suyunbek1399
      @suyunbek1399 6 лет назад

      Жиза

  • @TheTimeDilater
    @TheTimeDilater 7 лет назад +1

    seems like a deep breathtaking moment when you got the answer to be this long...

  • @jousif650
    @jousif650 7 лет назад +13

    It is too long, not too hard. Anyway I doubt anyone can do it in any exam without making a small mistakes ☺

    • @blackpenredpen
      @blackpenredpen  7 лет назад +9

      it's like running a marathon (well, almost...)

  • @KrisEditz29
    @KrisEditz29 5 лет назад +1

    Most elegant integral I've seen so far,thank you sir

    • @ktuluflux
      @ktuluflux 2 года назад

      Nothing even remotely elegant about this. This is the equivalent of opening a safe by dropping an anvil on it.

  • @citizenalex1934
    @citizenalex1934 6 лет назад +4

    "When in doubt, use horseshoe mathematics."

    • @craftbuzzwonky4752
      @craftbuzzwonky4752 3 года назад

      You too saw the video!!
      I see, you are a man of "NO U" culture here!

  • @aryanjha1302
    @aryanjha1302 Год назад +2

    Easiest integral on RUclips
    31 min yt video - "no i don't think i will"

  • @kylefarias9143
    @kylefarias9143 7 лет назад +13

    do the integral of sqrt(tan(cuberoot(tanx)))

    • @nejlaakyuz4025
      @nejlaakyuz4025 5 лет назад

      Kyle Farias Just use numerical integration on given bounds

  • @DougCube
    @DougCube 7 лет назад

    Integrand has a period of pi. It's real-valued from [0,pi/2) and complex-valued from (pi/2,pi). Goes to +inf at pi/2.

  • @LucBogaert
    @LucBogaert 7 лет назад +7

    Running a marathon is easy compared to solving this integral 🤓

  • @angelogandolfo4174
    @angelogandolfo4174 3 года назад

    That was a really enjoyable lil’ video. Thank you, it was a nice little refresher! 🙂

  • @Zhardamon
    @Zhardamon 7 лет назад +3

    pure beauty...!

  • @vishalmishra3046
    @vishalmishra3046 3 года назад

    Here is a simpler and reliable way to do any partial fraction, t = A (t^2-t+1) + (Bt+C) x (t+1) = (A + B) t^2 + (-A + B + C) t + (A + C). Therefore, A + B = 0 = A + C and -A + B + C = 1. Therefore, B = -A = C = 1/3. This is instead of plugging random values.

  • @TheKillerSock
    @TheKillerSock 7 лет назад +3

    yea dog imma need you to check by differentiation

  • @DavidSmyth666
    @DavidSmyth666 7 лет назад

    Very thorough explanation. As an idea for another integral video, this is one of the most difficult integrals I ever got in college :
    Integral [ 2x^3 / ( ( x^6 + 3 ) ^ (1/2) ) + ( 3x^2 / (4 - x^2) )^(1/6) ] dx
    From x=0 to x=1
    This could be the "scariest integral on RUclips" ;)

    • @arthagrawal4500
      @arthagrawal4500 Год назад

      It is like fx+f(inverese) x so ans will be 1*1

  • @LightYagami-on5lm
    @LightYagami-on5lm 6 лет назад +71

    When title says easy and time says half an hour
    🤔🤔🤔🤔🤔🤔🤔😱

  • @davidgillies620
    @davidgillies620 5 лет назад +1

    It's also expressible in terms of "the" hypergeometric function 2F1.

  • @Bludgeoned2DEATH2
    @Bludgeoned2DEATH2 7 лет назад +3

    Dr. BalckPenRedPen, please check the answer by differentiation :)

  • @taarchi
    @taarchi 7 лет назад

    An excellent video, explained clearly. Really enjoyed watching the video and even had a try myself after watching. Great job.
    我非常喜欢这个视频关于积分。黑笔红笔老师的解释清楚!看到了这个视频我自己试一试解决这个积分!

  • @robertherbert8419
    @robertherbert8419 7 лет назад +5

    ....It wasn't that bad....it didn't have limits to substitute (hehe ! )

  • @laxminarayanbhandari855
    @laxminarayanbhandari855 3 года назад +2

    My friend had given me this integral as a challenge and I had solved it. I would say this a great algebraic integration problem.

  • @Centauri902
    @Centauri902 7 лет назад +5

    now the nth root

  • @BRUBRUETNONO
    @BRUBRUETNONO 7 лет назад +2

    Tumbs up for this ace demonstration !!!

  • @ronnykazadi559
    @ronnykazadi559 6 лет назад +3

    Can you do integral of (xtanxdx) ?

  • @mabell01
    @mabell01 3 года назад +1

    It looks so innocent at the very beginning. lol

  • @jasoncetron233
    @jasoncetron233 4 года назад +5

    Small technical error:
    In the final function, you used the constant C to represent the constant of integration. BUT, you already used C to represent a different constant in your partial fraction decomposition. So, the final solution should use a different constant, like C-sub-1 or K.

  • @mike4ty4
    @mike4ty4 4 года назад

    Wolfram gives a general solution in terms of hypergeometric functions:
    int [tan(x)]^a dx = 2F1(1, (a+1)/2; (a+3)/2; -tan(x)^2) . ([tan(x)]^(a+1))/(a+1) + C
    In effect, a hypergeometric "correction" factor applied against a power rule-like construct operating on tan(x), as though you naively integrated it. Hence
    int [tan(x)]^(1/3) dx = 2F1(1, 2/3; 5/3; -tan(x)^2) . ([tan(x)]^(4/3))/(4/3) + C.
    which to me is a lot nicer. One of the things about maths is that there isn't one "true" or "best" _representation_ of a mathematical object, but unfortunately, the way it's taught conveys this idea that there is.

  • @thewatcherinthecloud
    @thewatcherinthecloud 7 лет назад +5

    ...And when you want to take a break from listening to this video, you are going to SUBSTITUTE IT for one of the easier/more beautiful ones to understand :D Like sin(z)=2

  • @gaspberries8445
    @gaspberries8445 Год назад

    For anyone wondering, the constant to make them equal is pi * sqrt(3) /12

  • @roceb5009
    @roceb5009 7 лет назад +3

    Okay so you've done sqrt tan x, you've done cube root tan x, can you generalize? Nth root tan x ?

  • @rohankodibagkar2552
    @rohankodibagkar2552 2 года назад +1

    "and then we have to get back to the U world, and then we have to go back to the X world."
    What a wild ride - we're going on interplanetary journeys solving this integral!

  • @Far_Gem
    @Far_Gem 7 лет назад +53

    It kinda bothers me that you write "tan^-1" instead of "arctan", it makes it seem like you could get tan^-(1/3) by multiplying it with tan^(2/3).

    • @MC-mx1mt
      @MC-mx1mt 7 лет назад +2

      Florian Bender if you mean 1/tan x, he would write it as cot x

    • @monzur1947
      @monzur1947 7 лет назад +14

      Florian Bender tan^-1 is a standard notation for arctan

    • @GrouchierThanThou
      @GrouchierThanThou 7 лет назад +29

      I agree. It's bad form IMO to both use tan^-1(x) for arctan(x) as well as the tan^q(x) for (tan(x))^q within a single exercise.

    • @angelmendez-rivera351
      @angelmendez-rivera351 7 лет назад +9

      Monzur Rahman We're aware, but it's a terrible notational standard.

    • @GrouchierThanThou
      @GrouchierThanThou 7 лет назад +2

      It's not even a "standard" notation really. Just a commonly used one (and not even as commonly used as the arctan notation).

  • @matteolorusso5523
    @matteolorusso5523 5 лет назад +1

    Wolfram Alpha says" you goddamn right boy"

  • @capjus
    @capjus 7 лет назад +76

    You can't impress a girl with it

    • @bmc868
      @bmc868 7 лет назад +48

      sure it's too smart for them....

    • @timstorer978
      @timstorer978 7 лет назад +62

      I disagree. Perhaps your trying to impress the wrong girls.

    • @azmath2059
      @azmath2059 7 лет назад +6

      No you can't impress the girls quite true, but you can impress them with the money you make if you're working in this particular field.

    • @General12th
      @General12th 7 лет назад +40

      If you can't impress your girl with this stuff...
      *you're not talking to the right girls*

    • @bmc868
      @bmc868 7 лет назад +3

      Almost all girls like money, luxury cars and spending time shopping. They want M-O-N-E-Y......and their math skills is +....+money+money+money......

  • @strider_1237
    @strider_1237 5 лет назад

    You're videos are awesome! Please keep posting :)

  • @v_saaam
    @v_saaam 7 лет назад +3

    Everytime he says 'something' I hear 'sensei' *_*

    • @JorgetePanete
      @JorgetePanete 7 лет назад +1

      Samarth Varshney or... passdee instead of positive. Forgive him, neither him or me are english ppl

  • @adichauhan3713
    @adichauhan3713 4 года назад

    Not even a single mistake . Great job bro