checking the answer of integral of sqrt(tan(x)) by differentiation

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  • Опубликовано: 9 авг 2017
  • Most difficult derivative question on my channel yet,
    checking the answer of integral of sqrt(tan(x)) by differentiation,
    hardest differentiation problem,
    math for fun,
    hard calc 1 derivative problem,
    blackpenredpen

Комментарии • 189

  • @tylerqueen8920
    @tylerqueen8920 7 лет назад +600

    It's just so beautiful...*tear falls slowly from eye*

    • @blackpenredpen
      @blackpenredpen  7 лет назад +72

      Tyler Queen you won the comment of this video!! I just pinned it!! What a wonderful comment!!

    • @pongwang9893
      @pongwang9893 5 лет назад +8

      @@blackpenredpen yeah , so brilliant . great

  • @AP12uZvfvag
    @AP12uZvfvag 7 лет назад +784

    Last time someone used chain rule so many times, slavery was still legal.

  • @stuartyellow1679
    @stuartyellow1679 7 лет назад +247

    Why you dont call the video "differentiat (-1/sqrt(2)*tanh^-1((sqrt(tan(x))+sqrt(cot(x))/sqr
    OK i got it

  • @joelottosson1297
    @joelottosson1297 7 лет назад +107

    You like when they cancel out don't you

  • @whiz8569
    @whiz8569 7 лет назад +95

    "Don't be intimidated cause I did 1+1=2 again."
    I see what you did there.

  • @bastianherrera2171
    @bastianherrera2171 7 лет назад +121

    I've watched most of your videos and they are amazing, mainly because of the clear way you solve the problems. I've learnt so much about calculus with you, thank you very much! Keep making these amazing videos!

    • @blackpenredpen
      @blackpenredpen  7 лет назад +27

      Thank you for the supporting message! Will do!

    • @morganthem
      @morganthem 7 лет назад +5

      blackpenredpen I second this, they are amazing and clear

    • @AhnafAbdullah
      @AhnafAbdullah 7 лет назад +2

      I did this derivative after he put out the sqrt(tan x) but before this video, it was so beautiful :-:

    • @JeronimusJack
      @JeronimusJack 7 лет назад +2

      oh yea that's excatly how i feel, too. my old math tutors always wanted me to break more about it instead of telling me how it's done, but sometimes i was just stuck, here i get answers. i did the derivation afterwards myself :D and it worked. it's better to learn this way since i can explore and my stress level stays down hehe. it's not torture but tutoring here. ty

  • @tcocaine
    @tcocaine 7 лет назад +6

    I love how in the thumbnail you just wrote craziness instead of the whole shablang. I absolutely adore it.

  • @throxs1535
    @throxs1535 7 лет назад +40

    I feel like you're really getting the hang of this now :) going slow where need be... Going faster where allowed... This all comes together in a very fluent yet easily understandable explanation :) keep it up!

    • @blackpenredpen
      @blackpenredpen  7 лет назад +14

      Throxs MC thanks!!!! I think it's bc I have been just doing higher level math lately so it was easier to get the pace right.

  • @mrbenwong86
    @mrbenwong86 3 года назад +8

    After 15 minutes, I forgot I am doing differenitation, I almost want to put +c at the end.

  • @agabe_8989
    @agabe_8989 4 года назад +16

    That beast was too long that he had to type "integral of sqrt(tan(x))".

  • @DancingRain
    @DancingRain 7 лет назад +17

    That was epic!
    The most amazing mathematical simplification I've ever seen.

  • @dizilloHT
    @dizilloHT 7 лет назад +6

    wow finished my calculus class this year, and i dont believe i will see it again, but wow im so amazed by it. Keep up with the videos you help a lot of people with them!

  • @turkishwagnerian
    @turkishwagnerian 7 лет назад +51

    "I chose mathematics to honor the human mind"
    Carl Gustav Jacob JACOBİ

  • @Sid-ix5qr
    @Sid-ix5qr 5 лет назад +6

    d/dx(craziness)
    Let's do L-sub.
    l=cr
    d/dx(laziness).

  • @soyoltoi
    @soyoltoi 5 лет назад +15

    tanx for the video

  • @furo822
    @furo822 7 лет назад +48

    I think this is better.
    For the 1/(tanx + cotx)
    Multiply both sides with tanx
    ->tanx/(tan^2(x) +1)
    and the bottom part becomes sec^2(x)
    Finally everything just cancelled out and sqrt(tanx) remains
    That was funny btw

    • @blackpenredpen
      @blackpenredpen  7 лет назад +16

      YungHong Kung ahhhhhhh that's better!!!

  • @flowingafterglow629
    @flowingafterglow629 2 года назад +3

    So I watched the integral of root(tan x) the other day, and therefore had to watch this.
    I like the way you were smiling through the whole thing. I was just laughing the whole time, it is so beautiful to see. Every time something would fall out, I would just laugh some more.
    Amazing.

  • @Magic73805
    @Magic73805 6 лет назад +6

    Really, You're great sir.
    You are the master of "Calculus".

  • @user-mt9ux2di6u
    @user-mt9ux2di6u 3 года назад +4

    I really love how it all just collapses down to sqrt tan x

  • @weerman44
    @weerman44 7 лет назад +4

    Yet again, an amazing video with such a clear explanation

  • @MRBYRNO2505
    @MRBYRNO2505 5 лет назад +2

    holy mother of god, if i saw this a few years ago i would not have chosen to study maths at Alevel. seeing it now just brings a tear to my eye its so beautiful

  • @azmath2059
    @azmath2059 7 лет назад +1

    That's a great deal of work! Thanks for posting. Brilliant

  • @kornelviktor6985
    @kornelviktor6985 3 месяца назад +2

    Its so nice to see that he gets very excited when he sees that the answer will be sqrt(tanx).

  • @samirgeiger1042
    @samirgeiger1042 6 лет назад

    This is just so amazing. Great work! Such beutiful derivatives

  • @snejpu2508
    @snejpu2508 6 лет назад +57

    0:05 "We'll be differentiating this chinese expression". : )

  • @tomatrix7525
    @tomatrix7525 4 года назад

    That is a beautiful piece of art my friend

  • @ttg001
    @ttg001 7 лет назад +7

    I'm holding back tears....... This video is so powerful

  • @dakotaroberson9921
    @dakotaroberson9921 7 лет назад +2

    Wow great proof!! it was so great to see it all come together at the end lol

  • @drewski91
    @drewski91 6 лет назад +6

    i started crying at the sheer beauty of this math

  • @AlmightyMatthew
    @AlmightyMatthew 7 лет назад +1

    just perfect. satisfaction at the end was through the roof

  • @shiina_mahiru_9067
    @shiina_mahiru_9067 7 лет назад +3

    at 10:24, instead of changing tan x in terms of sin x and cos x, I would just multiply sqrt (tan x) both upstair and downstair to the second fraction. That should be the first thought because you want to end up with sqrt (tan x) after all the simplification, and to make it happen, sqrt (tan x) must be in the numerator

  • @bartj777
    @bartj777 7 лет назад

    Bravo, sir. Very impressive.

  • @berenjervin
    @berenjervin 5 лет назад

    Great video. Makes me want to go back to uni for a math degree after I retire!

  • @MurakDurak
    @MurakDurak 7 лет назад +2

    integral of sprt(tanx)dx has to be my favourite integral, but differentiating it is even more crazy!

  • @Galileo2pi
    @Galileo2pi 6 лет назад

    Great, keep going please

  • @bsul03420
    @bsul03420 7 лет назад +1

    Excellent, but now I have to differentiate my inverse coth expression to show it's the same!

  • @johnsalkeld1088
    @johnsalkeld1088 4 года назад

    At the stage of getuve rid of tan plus cot recall that this is cot * [1+tan^2] so cot * sec^2 easier I think due to direct cancelation and resolving the full Eqn to 1/(cot * tan^1/2 ) or tan ^1/2. but from a pedagogical standpoint I see that using a standard method is good

  • @MrPhilipp456
    @MrPhilipp456 7 лет назад

    This is insanity! I love it

  • @Xeotroid
    @Xeotroid 3 года назад +2

    1a) Integrate sqrt(tan x).
    1b) Check the answer of 1a by differentiation.
    1c) Prove 1b.

  • @JulianOnions
    @JulianOnions 6 лет назад

    This is amazing!

  • @cheeragsridhar1696
    @cheeragsridhar1696 3 года назад

    It’s so awesome
    The rate of terms falling from my eye is differential

  • @MarkMcDaniel
    @MarkMcDaniel 5 лет назад

    Brutal, but satisfying as hell.

  • @TheYoshi463
    @TheYoshi463 7 лет назад +5

    Yay, blackpenbluepenredpen made a new video!

  • @BRUBRUETNONO
    @BRUBRUETNONO 7 лет назад

    Ace derivative master ;)

  • @IISH4RKZzII
    @IISH4RKZzII 7 лет назад

    This is SOOO DOPE !!!

  • @July__-eu5pd
    @July__-eu5pd 5 лет назад

    Wow you actually differentiated it :p

  • @axel15473
    @axel15473 7 лет назад +7

    He is so on fire XD

  • @Lily-zd6dx
    @Lily-zd6dx 6 лет назад

    Mindblow

  • @anthonysteinerv
    @anthonysteinerv 6 лет назад

    I used trigonometric substitution for both of the integrals and got the exact same inverse tanget but I got a logarithm, the thing is that I did the derivative of that anseer and I didn't get the square root of tangent x, actually I got the sine of 2x, I need help bro.

  • @wydadiyoun
    @wydadiyoun Год назад

    How about starting from square tangent and find that expression by integrating

  • @eetuhaavisto524
    @eetuhaavisto524 7 лет назад +2

    Hey blackpenredpen can you solve this derivative next time with the definition of derivative? That ought to be an interesting limit(needless to say that very fun as well)😂

    • @blackpenredpen
      @blackpenredpen  7 лет назад +8

      I prob. will have to use 4 classrooms for that...

  • @helved807
    @helved807 3 года назад

    this is the most satisfying differentiation

  • @TheScienceGuy10
    @TheScienceGuy10 5 лет назад +1

    Could you please do a video of integration of sqrt tanx? The other way round. I've been trying it out but getting stuck. Would really appreciate it.

    • @jmannthemann4793
      @jmannthemann4793 5 лет назад +2

      Siddhartha Pundit He already has, just look for it

  • @dyer308
    @dyer308 7 лет назад +10

    Please show us Feynmans trick on integral solution of sinx/x without a power series solution!!!!!!

    • @calcul8er205
      @calcul8er205 7 лет назад

      raees khan Another cool way that uses the idea of multiplying the integrand by e^(-st) is by double integral and Laplace transform

  • @bhavydugar6665
    @bhavydugar6665 2 года назад

    This is just so coooool
    I took its SS and made it my wallpaper

  • @garomo6384
    @garomo6384 7 лет назад

    amazing !!!!

  • @XXgamemaster
    @XXgamemaster 5 лет назад

    Beautiful.

  • @Justiin_rm
    @Justiin_rm 4 года назад

    Woaaaa

  • @gvchas
    @gvchas 4 года назад +1

    Everything is possible. Just believe in your math!

  • @alomirk2812
    @alomirk2812 2 года назад

    Just wanted to point, this is the solution of the integral but it is undefined in the reals, if you will extend it to the complex numbers it will be defined and give you a real number

  • @AdrianMartinez-lt4dz
    @AdrianMartinez-lt4dz 7 лет назад +2

    Man! You're a genius 👌
    Now do it in chinese xD

  • @fakeplaystore7991
    @fakeplaystore7991 11 месяцев назад

    This is evil sorcery, pure and simple.

  • @vibhupandya6103
    @vibhupandya6103 4 года назад

    Hey in sqrt cotxtanx won't it be = sqrt1=±1???

  • @osvaldomena1172
    @osvaldomena1172 7 лет назад

    Amazing man

  • @axel15473
    @axel15473 7 лет назад

    Oooohhhhh yessss. I wait for that. The other way

  • @wellbangok8959
    @wellbangok8959 7 лет назад +12

    I'm a simple guy. blackpenredpen uploads a video, I watch.

  • @elementalsheep2672
    @elementalsheep2672 6 лет назад +1

    from about 12:00 onwards you could hear him getting more and more excited

  • @ReubenMason99
    @ReubenMason99 7 лет назад

    Could you possibly do some more detailed explained integration videos for people who don't know much calculus

    • @francoisgatine4106
      @francoisgatine4106 7 лет назад +2

      There is a youtube channel called Professor Leonard (hope I wrote it correctly) who records himself teaching several maths classes. He's a really good teacher in my opinion, it can help you with understanding calculus. No, it isn't boring.

    • @blackpenredpen
      @blackpenredpen  7 лет назад +2

      Reuben Mason hi. U can also check out my playlists. www.blackpenredpen.com/math/Calculus.html

    • @kindlin
      @kindlin 7 лет назад

      That's a detailed list. How did you have the time to put all that together with all your regular classes/study etc.?

  • @PackSciences
    @PackSciences 7 лет назад +1

    Valid forall x in [0;pi/2[ mod 2pi.
    You could have made it more impressive using the formula arctan(x) + arctan(1/x) = sign(x) * pi/2 in order to get an uglier expression.

  • @id120266737
    @id120266737 7 лет назад

    You're a fucking genius.

  • @chessandmathguy
    @chessandmathguy 7 лет назад

    beautiful. just beautiful.

  • @user-gt1cn2tf7s
    @user-gt1cn2tf7s Год назад

    Miraculo!

  • @ToeNailMuncher111
    @ToeNailMuncher111 3 месяца назад

    How does he do the chain rule so fast

  • @wduandy
    @wduandy 7 лет назад

    Love you

  • @imcalculus
    @imcalculus 4 месяца назад

    Do this with definition of a derivative

  • @ck7671
    @ck7671 6 лет назад

    8:19 simplify the 2/sqrt(2)^2 !!

  • @ExiDJuicy
    @ExiDJuicy 7 лет назад +21

    Missing "+C" at the beginning 😎

  • @AnOrrangeShirt
    @AnOrrangeShirt 5 лет назад

    Would it be possible to integrate sqrt(tan(x)) twice?

  • @mbrq1196
    @mbrq1196 7 лет назад

    Waw

  • @golocok
    @golocok 5 месяцев назад

    Un final de cálculo que te haga resolver la integral de la raíz cuadrada de la tangente y luego derivar para demostrar que el resultado estaba bien. No aprueba nadie. :D

  • @arekkrolak6320
    @arekkrolak6320 7 лет назад +9

    If you have to remember derivative of arc tanh then you can also remember what id the final result :) be a real man and use definition of derivative! ;)

  • @upanshulakhani6221
    @upanshulakhani6221 4 года назад

    That's nice but why don't you check the answer by integration

  • @colleen9493
    @colleen9493 5 лет назад

    Now to the integral of the integral of sqrt(tan x)

  • @lalitverma5818
    @lalitverma5818 6 лет назад

    I can't imagine

  • @yahyabajdadi516
    @yahyabajdadi516 6 лет назад

    How about differentiating sqrt^3(tanx)?

    • @natan9065
      @natan9065 6 лет назад

      Yahya Bajdadi d/dx((tanx)^(3/2))
      = (2/3)(tanx)^(1/2)•(secx)^2
      By the chain rule

  • @yopxy6188
    @yopxy6188 5 лет назад

    Do it with limits

  • @azzteke
    @azzteke 3 года назад

    Almost nowhere in the world are the sec and cosec still taught.

  • @afsarshaikh9654
    @afsarshaikh9654 7 лет назад +1

    Mind Fucking Blown. Just see how beautiful that is!

  • @ily9565
    @ily9565 7 лет назад

    What happened to your friends shoe?

  • @upanshulakhani6221
    @upanshulakhani6221 4 года назад

    Now check the answer by integrating

  • @physicsphysics1956
    @physicsphysics1956 6 лет назад

    Where is the mistake?

  • @majkgmajkg2613
    @majkgmajkg2613 7 лет назад

    I'm sorry early too... In my country is 0:14 am. On 7 I have job... Shit...

  • @Gawkie
    @Gawkie 7 лет назад +67

    a real asian wouldve done it using the definition...just sayin'

    • @paulosouza449
      @paulosouza449 5 лет назад +9

      Really wonder how would that look like

    • @midlandscoder
      @midlandscoder 5 лет назад +6

      He'd need the whole wall to do that hahahaha

    • @ChrisChoi123
      @ChrisChoi123 5 лет назад +1

      using what definition? i dont think i quite follow...

    • @danielmastalerz3640
      @danielmastalerz3640 5 лет назад +2

      definition of derivative, the limit, check on Wikipedia

    • @ferrumarctus
      @ferrumarctus 4 года назад +4

      @@ChrisChoi123 derivative of a function f(x) is defined as the limit when h -->0 of [f(x+h)-f(x)]/h

  • @levi4328
    @levi4328 7 лет назад

    o boi i'm so early

  • @agustindominguezcruz5000
    @agustindominguezcruz5000 4 года назад

    Now do it by the derivative definition

  • @gloystar
    @gloystar 4 года назад

    What a mess LOL!

  • @200Exotic-Topic
    @200Exotic-Topic 2 года назад

    Integrate your answer again to double check

  • @maxhaibara8828
    @maxhaibara8828 7 лет назад

    what's the derivative/integral of N! (factorial of N) ?

    • @MagicGonads
      @MagicGonads 7 лет назад

      No idea, but I found interesting that n! = int(0->+inf) (x^n e^-x dx) for x > -1
      (Found that by accident)
      also written as int(0->+inf) (e^(n*ln(x)-x)dx)

    • @maxhaibara8828
      @maxhaibara8828 7 лет назад

      wow he need to make a video about this

    • @MagicGonads
      @MagicGonads 7 лет назад

      It's not a derivative because it has both n and x, but still suprising.

    • @MagicGonads
      @MagicGonads 7 лет назад

      www.desmos.com/calculator/oukquiyntu

    • @MagicGonads
      @MagicGonads 7 лет назад

      www.desmos.com/calculator/balkjdohcq
      The curves are calculated, not derived.

  • @stolenmonkey7477
    @stolenmonkey7477 2 месяца назад

    I kinda just went along with the ride lol, wow

  • @pepemeade8845
    @pepemeade8845 4 года назад

    Holy jesus...