i-th root of i

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  • Опубліковано 20 вер 2017
  • We will solve the most complex math question, i.e. evaluating the principal value of the i-th root of i, namely i^(1/i). In fact, the answer is actually a real number!
    Do you enjoy complex numbers and up for a challenge? If so, check out x^x=i • they never teach equat...
    🛍 Shop my math t-shirt & hoodies: amzn.to/3qBeuw6
    💪 Get my math notes by becoming a patron: / blackpenredpen
    #blackpenredpen #math #calculus #apcalculus

КОМЕНТАРІ • 602

  • @blackpenredpen
    @blackpenredpen  8 місяців тому +29

    Do you enjoy complex numbers and up for a challenge? If so, check out x^x=i ua-cam.com/video/vCdChDmMYL0/v-deo.html

    • @vincentkingsdale8334
      @vincentkingsdale8334 7 місяців тому

      How is this practically applied to real life????

    • @Unlimit42
      @Unlimit42 Місяць тому

      You can't solve subfactorial of i.

  • @pseudotenshi3431
    @pseudotenshi3431 3 роки тому +382

    The most surprising thing about this is
    I understood more than half of what he explained

  • @michaelliu8887
    @michaelliu8887 4 роки тому +1249

    *Learns about imaginary numbers*
    UA-cam:
    What's 1/i?
    What's e^i?
    What's i^i?
    What's sqrt(i)?
    What's log(i)?
    What's i-th root of i?
    What's sin i?
    What's sin-1(2)?
    What's i factorial?
    What's integral of x^i?

    • @blackpenredpen
      @blackpenredpen  4 роки тому +133

      刘颢云 lolll

    • @Ramu-10
      @Ramu-10 3 роки тому +47

      Ya got lucky...
      I haven't even learned about logarithms and have no clue what e is...

    • @papaganush420
      @papaganush420 3 роки тому +26

      @@Ramu-10 you gotta love when you figure out whats going on

    • @valeriolocatelli665
      @valeriolocatelli665 3 роки тому +17

      @@Ramu-10 it is euler's number, which approxamatly is 2.71.......

    • @nuzlock4481
      @nuzlock4481 3 роки тому +9

      @@Ramu-10 then watch this amazing video about "e" and it's derivation.
      ua-cam.com/video/m2MIpDrF7Es/v-deo.html

  • @hyperpsych6483
    @hyperpsych6483 5 років тому +1279

    0:32
    "I don't like to be on the bottom, I like to be on the top"
    Me: *scrolls down to comments to see if anyone made a joke about that*

    • @hendrik5919
      @hendrik5919 5 років тому +9

      A joke would be like what?

    • @TheLifeofJay1
      @TheLifeofJay1 5 років тому +29

      Super Psych that is literally exactly what I just did 😂😂😂 you made my day

    • @paulgoogol2652
      @paulgoogol2652 4 роки тому +8

      I assume the top would be the video section, while the bottom is the comment section.

    • @rogerkearns8094
      @rogerkearns8094 4 роки тому +4

      In the video it's already meant to be a joke.

    • @kabochaVA
      @kabochaVA 4 роки тому +17

      Same here...
      0:32 "That's what she said!" xD

  • @willy3506
    @willy3506 6 років тому +770

    Do the e-th root of i and the i-th root of e

    • @lyrimetacurl0
      @lyrimetacurl0 5 років тому +59

      The second one is easy:-
      e^(i*pi) = -1
      ith root of e = e^(1/i)
      So (ith root of e)^(pi*i^2) = -1
      So (ith root of e)^-pi = -1
      Flip over fraction
      So (ith root of e)^pi = -1
      We know e^(i*pi) = -1
      So (ith root of e) = e^i
      That's a distance of 1 radian around the unit circle
      So (ith root of e) = cos(1)+i*sin(1)
      Or about 0.54030 + 0.84147i

    • @anselmschueler
      @anselmschueler 5 років тому +20

      just go on wolfram|alpha

    • @camerongray7767
      @camerongray7767 5 років тому +1

      Lyri Metacurl
      Lol

    • @dnpendown3199
      @dnpendown3199 5 років тому +7

      @@anselmschueler wtf

    • @anselmschueler
      @anselmschueler 5 років тому +4

      @@dnpendown3199 Or use Qalculate, the best desktop and command line calculator available!
      > root(i,e), root(e,i)
      [root(i, e), root(e, i)] = approx. [0.8376315 + 0.54623573i, 0.54030231 - 0.84147098i]

  • @dallasboringnews7157
    @dallasboringnews7157 4 роки тому +1006

    "i" understand this a whole lot better now.

  • @austinlincoln3414
    @austinlincoln3414 3 роки тому +118

    “I dont like to be on the top. I like to be on the bottom” - blackpenredpen

  • @obinnanwakwue5735
    @obinnanwakwue5735 6 років тому +313

    Wow, complex roots of imaginary numbers are real......math is so weird!

    • @ffggddss
      @ffggddss 6 років тому +9

      Sometimes they are, but not usually.

    • @stranger0152
      @stranger0152 6 років тому +67

      But bro real root of real numbers is also imaginary. For example square root of -1 😂

    • @gaeb-hd4lf
      @gaeb-hd4lf 4 роки тому +8

      @Smash Boy Yeah, technically speaking Complex numbers are just an algebraic estructure made from real numbers (just like matrices for example) so it makes sense that if you apply a function to an "imaginary" number (a number on the Y axis of the complex plane) it gives you a "real" number (a number on the X axis of the complex plane).

    • @philiptymon3380
      @philiptymon3380 4 роки тому +12

      because “One of the miseries of life is that everybody names things a little bit wrong.” - Richard Feynman 1985.

    • @saswatsarangi6669
      @saswatsarangi6669 4 роки тому +1

      Purely imaginary in this case, imaginary root of imaginary...

  • @Rose-vb4wk
    @Rose-vb4wk 6 років тому +122

    Or you could just
    i = e^(iπ/2)
    ith root both sides
    i√i = e^(π/2)

    • @arthurmoiret6076
      @arthurmoiret6076 3 роки тому +2

      +2kπ ?

    • @dns911
      @dns911 3 роки тому +8

      @@arthurmoiret6076 That's the point when he said there are infinitely many solutions to this

    • @adityasharma2380
      @adityasharma2380 3 роки тому

      I did that too!!!!!

    • @diegocabrales
      @diegocabrales 3 роки тому

      @@arthurmoiret6076 or -2kπ

  • @trip_on_earth
    @trip_on_earth 6 років тому +38

    I'm in love with mathematics now

    • @D1M1T
      @D1M1T 3 роки тому +4

      I was in love with math. Then they said “do specialists”

  • @cangursoy
    @cangursoy 6 років тому +11

    I just stumbled upon your videos while procrastinating. You're a really warm and enthusiastic talker, keep it up sir! :)

  • @SoumilSahu
    @SoumilSahu 6 років тому +60

    black mic red shirt yay!

  • @travishayes6037
    @travishayes6037 6 років тому +184

    As mentioned before, I love this channel. Found it randomly, but so glad I did.
    Currently a grad student taking complex analysis (as an elective, took it 2years ago). All of your complex videos are just supplementary/review for me, but they're still very satisfying to watch.
    Got any plans for singularities?

    • @blackpenredpen
      @blackpenredpen  6 років тому +21

      Travis Hayes great idea! I will discuss this with peyam bc we are filming together this Friday

    • @retired5548
      @retired5548 6 років тому +4

      in a sense,all of his videos are complex

    • @retired5548
      @retired5548 6 років тому +1

      in two,actually. at least two

    • @normanbraslow7902
      @normanbraslow7902 3 роки тому +1

      I don't believe a word of what you say! You doubtless are as flummoxed as the rest of us mortals. Quit showing off!

  • @tracychacon1210
    @tracychacon1210 9 місяців тому +2

    This video is amazing. Thank you for the break down!

  • @RizzY_RUS
    @RizzY_RUS 4 роки тому +20

    Drink game:
    Take a shot after he says the letter "i"

    • @skullzs1983
      @skullzs1983 3 дні тому

      You'd get drunk after the first 10 seconds.

  • @martinhughes2637
    @martinhughes2637 3 роки тому

    This is so fantastic and beautiful. Thank you for sharing!!

  • @Fematika
    @Fematika 6 років тому +14

    The reason why i^i = e^(-pi/2) is because i^i = e^(log(i)i) = e^((pi/2)i * i) = e^(-pi / 2). There are infinite answers because the log(z) has infinite answers; as it is defined as ln |z| + arg(z)i, where arg(z) is the angle (which can be, in this case, pi/2, 5pi/2, 7pi/2, ...).

  • @suryanshkhatri7929
    @suryanshkhatri7929 3 роки тому +6

    This guy rekindles our faith in the fact that things that seem to be very tough, are actually very easy, we just need to take one right step, and everything else becomes so easy!

  • @parthiban5663
    @parthiban5663 4 роки тому +1

    Your voice is a lullaby 😭❤️

  • @anirudhbhalekar
    @anirudhbhalekar 6 років тому +18

    You're explanations are simple and crisp, really helping me learn mathematics better

  • @Treegrower
    @Treegrower 6 років тому +272

    You are a math god

  • @fountainovaphilosopher8112
    @fountainovaphilosopher8112 6 років тому +182

    Who thinks new BPRP is more interesting and better? *raises hand*

    • @blackpenredpen
      @blackpenredpen  6 років тому +8

      Ognjen Kovačević thank you!!!

    • @maxhaibara8828
      @maxhaibara8828 6 років тому +3

      yay!!

    • @blackpenredpen
      @blackpenredpen  6 років тому +12

      Ognjen Kovačević u know. It's weird that even tho I teach the same way in my classes. But I have been doing different things on YT nowadays and I have been enjoying it way more also.

    • @maxhaibara8828
      @maxhaibara8828 6 років тому +4

      blackpenredpen wait you're a teacher?! I thought you're just a super smart student!!

  • @devjain2319
    @devjain2319 3 роки тому +7

    e, pi, and i: The Zeus Poseidon and Hades of math

  • @camerongray7767
    @camerongray7767 5 років тому +14

    I don’t even know how to begin to do this

  • @rolexmarcelo3218
    @rolexmarcelo3218 3 роки тому +7

    I'm even more amazed that you can formulate these math questions with answers.

  • @davidkippy101
    @davidkippy101 6 років тому +10

    You could actually just start with e^(ipi)=-1. Take the square root of both sides: e^(ipi/2)=i. Then take the ith root of both sides. e^(pi/2)= i^(1/i).

  • @arf101088
    @arf101088 5 місяців тому

    such an interesting edge case!

  • @dane1234abc1
    @dane1234abc1 3 роки тому

    You are the most brilliant math person I have ever come across. I am in awe.

  • @knnedmeitei3323
    @knnedmeitei3323 5 років тому

    Great work. Thank u

  • @kevinpaulsen6103
    @kevinpaulsen6103 5 років тому

    I love it when blackpenredpen features blackpenredpen.

  • @brandongammon6978
    @brandongammon6978 5 років тому

    That shirt is crazy!! Also, I love your vids ! 😄

  • @japeking1
    @japeking1 6 років тому

    These just make me so cheerful..... I have to limit myself to one a day ( and then I'll start again from the beginning because I'm still forgetting stuff like when I was a kid. )

  • @thibautklinger5178
    @thibautklinger5178 3 роки тому

    When I saw the video I took a few minutes to think about it for myself and then come back to see if I was right and I was. Thanks I like keeping my mind sharp with little math riddles like this one.

  • @isavenewspapers8890
    @isavenewspapers8890 2 роки тому +2

    Euler’s number and pi, name a more iconic duo

  • @somyaranjanpanda4620
    @somyaranjanpanda4620 4 роки тому

    Thank you sir🙏🙏🙏

  • @joshtechindia
    @joshtechindia 6 років тому +46

    YAY!
    This was interesting!

    • @1234vedas
      @1234vedas 5 років тому

      Emmanuel Franklin your name n your profile matches a lot with a malayali. Are you one?

  • @KalikiDoom
    @KalikiDoom 6 років тому +3

    amazing!

  • @GrowlyBear917
    @GrowlyBear917 3 роки тому +1

    I'm going to use this information when I file my taxes.

  • @harrisonoberg8085
    @harrisonoberg8085 2 роки тому +1

    i blinked and he got pi out of seemingly nowhere

  • @Vince0
    @Vince0 6 років тому +3

    That ball that you always keep in your hand makes you look like an ood from DW xD

  • @danialbrown4417
    @danialbrown4417 4 роки тому

    Black pen blue pen would make it easier for my eyes to read. Thank you so much for your videos.

  • @raiturner2132
    @raiturner2132 5 років тому +20

    0:33 that’s what she said😂😂

  • @dhyeypatel8399
    @dhyeypatel8399 6 років тому +8

    That was the question that i had not been able to solve in my exam thanks

  • @notthefez3634
    @notthefez3634 3 роки тому +1

    I just wasted 2 minutes being confused by a problem I never even knew existed and still don't understand

    • @WorriedtheCircusDemon
      @WorriedtheCircusDemon 3 роки тому

      Damn, same, I clicked this in my recommended (I've always been horrible at math) I don't get how people in the comments get it so easily

  • @krimbus1236
    @krimbus1236 5 місяців тому +1

    Another way to do this is using De Moivre’s theorem, where i on the complex plane would be pi/2, so theta is pi/2/i, so e^i theta would simplify to e^pi/2

  • @radward7173
    @radward7173 Рік тому

    damn I didn't know about imaginary numbers more than how to write them and how to show them on complex plain. yet after watching several other videos of yours I managed to get this one by myself.

  • @AtariDays80
    @AtariDays80 3 роки тому +7

    I still find it odd that "i" with absolute magnitude of "1" can ever twist itself into something outside of that, as in > 1.

  • @nisithranjanhazra9298
    @nisithranjanhazra9298 3 роки тому

    Thanks for your smile too ❤️

  • @EdKolis
    @EdKolis 9 місяців тому +3

    Imagine if imaginary roots of other imaginary things could be real. Like trees.

  • @shotasdg3679
    @shotasdg3679 6 років тому

    Beautiful!

  • @markjackson6642
    @markjackson6642 6 років тому +1

    Amazing!!!

  • @philipyao5989
    @philipyao5989 6 років тому +170

    Wait ur a teacher!?

    • @blackpenredpen
      @blackpenredpen  6 років тому +71

      Philip Yao yes i am

    • @maxhaibara8828
      @maxhaibara8828 6 років тому +52

      blackpenredpen you're so young that we thought you're a 20-years old math youtuber haha

    • @victorvega8061
      @victorvega8061 5 років тому +2

      @@blackpenredpen where do you teach I have to go there (つ°ヮ°)つ

    • @hherrera007
      @hherrera007 4 роки тому +2

      Nop, he is a math god.

    • @sals4659
      @sals4659 4 роки тому +1

      @@victorvega8061 UC Berkeley

  • @mikeCavalle
    @mikeCavalle 2 роки тому +1

    nicely done.... the use of multi color to force focus reminds me of a math professor in the 1960's at the University of Maine.

  • @shibsankarnaskar357
    @shibsankarnaskar357 3 роки тому

    Really impressive..
    💗💗

  • @SNOWgivemetheid
    @SNOWgivemetheid 2 місяці тому +1

    I did some other method : Consider i^(1/i) and get i = (-1)^(1/2) and -1=e^iπ so finally : i=e^(iπ/2) so in the end we have i^(π/2) as the "i"s cancel out !

  • @TuanLe-td1dg
    @TuanLe-td1dg 4 роки тому

    That was so clean, damn

  • @czerbniak75
    @czerbniak75 3 роки тому

    Tak na dobry sen. U mnie luzik. Dobranoc, kurde jeszcze jasno.

  • @HanzCastroyearsago
    @HanzCastroyearsago 2 роки тому

    “I dont like to be on the bottom, i like to be on the top”
    - pen guy

  • @charles7623
    @charles7623 6 років тому

    thank you

  • @squeet6831
    @squeet6831 5 років тому +5

    0:33 of course you do. Your entire channel is about doing hard work. Lol

  • @flamingpaper7751
    @flamingpaper7751 6 років тому +7

    What would an ith root(x)graph look like?

  • @dariofervenza808
    @dariofervenza808 6 років тому +1

    wow that is like magic! amazing!

  • @maxhaibara8828
    @maxhaibara8828 6 років тому +36

    but the real question is... what is i-th root of i based on Wolfram Alpha?

    • @blackpenredpen
      @blackpenredpen  6 років тому +10

      Max Haibara lol!!!!

    • @MattMcIrvin
      @MattMcIrvin 5 років тому +4

      Just tried it... it says what he said

    • @Pacvalham
      @Pacvalham 5 років тому +1

      I just did it before reading the comments, then I did e^(pi/2), then I compared the decimals, and they are the same, so W|A agrees.

    • @victorvega8061
      @victorvega8061 5 років тому

      @@MattMcIrvin The joke is that you don't need Wolfram Alpha to solve seemingly difficult equations.

    • @snbeast9545
      @snbeast9545 4 роки тому

      Even calculators can compute it, and they give the same answer. (Done on a TI-84)

  • @HelloWorld72459
    @HelloWorld72459 3 роки тому

    'THATS IT' PROCEEDS TO VANISH IN THIN AIR

  • @amineelarif7001
    @amineelarif7001 4 роки тому

    The ad is trying to kill the youtuber 🤣

  • @darkalpha6530
    @darkalpha6530 3 роки тому +1

    So you have this chanel too.
    Subscribed to this too ❤️❤️🔥🔥😂😂👍👍.

  • @alexeypopov314
    @alexeypopov314 10 місяців тому

    Dude, you rule!

  • @Lily-zd6dx
    @Lily-zd6dx 6 років тому +2

    "What we do now? We do our usual business" if math was that easyyy

  • @NardiPaffon
    @NardiPaffon 2 роки тому

    "Let me do a REAL quick video for you" I see what you did there

  • @p1xelat3d
    @p1xelat3d 2 місяці тому

    0:30 the quote of all time

  • @billf7585
    @billf7585 3 роки тому +1

    You can check its true, if you raise both sides to the power i, you get i = e^(i*pi/2) which is the complex polar form of a vector with argument pi/2 and magnitude 1, which is of course just i on the complex plane. The family of solutions are associated with all arguments that equal pi/2 mod 2pi, so any integer number of times around the units circle landing back at i.

  • @112BALAGE112
    @112BALAGE112 6 років тому +1

    There are other solutions as well: (e^(pi/2+2*n*pi))^i = i for integers n.

  • @karrarghalb3015
    @karrarghalb3015 3 роки тому

    Nice, thank you

  • @SwasthikVideos
    @SwasthikVideos 4 роки тому

    Very good and nice videos with interesting content sir

  • @pt-xyzt-9826
    @pt-xyzt-9826 6 років тому

    You re great! :)

  • @samuelwillowcreek8764
    @samuelwillowcreek8764 3 роки тому

    That moment when you try to checkmate a grandmaster and he just literally flips the board. Great stuff man, I didn't this was a question that bothered me since 3 minutes ago but thanks for the answer anyways.

  • @alparslan9862
    @alparslan9862 5 років тому

    Spectacular example solution.

  • @cleiven3533
    @cleiven3533 5 років тому +2

    Could one also write i^(1/i) as (e^(pi/2)i)^(1/i), because e^(pi/2) = i according to Euler's formula, allow the i and 1/i to cancel out, and take the remaining e^(pi/2) as a final answer?

  • @marcusrosales3344
    @marcusrosales3344 5 років тому

    You could easily motivate this by analogy with a square root. Like square root of 4 can be found by finding a number a such that:
    a^2=4 ==>a=2.
    Similarly, the ith root of i means find an a such that:
    a^i=i ==> a=e^(pi/2)

  • @BeIteshazzar
    @BeIteshazzar 3 роки тому

    hush, hush... i to i.. too shy, shy..

  • @ChadCynical
    @ChadCynical 6 років тому +4

    That was pretty neat.

  • @fpgamer4566
    @fpgamer4566 3 роки тому

    That mic kinda look like a cartoon bomb

  • @TheMartnK
    @TheMartnK 6 років тому +3

    You should probably also update this version with e^(pi/2+2*pi*n)

  • @maddurihemant9157
    @maddurihemant9157 6 років тому +1

    Sir there can also be my method:
    Let i^1/i=x
    Take ln both sides..
    Now 1/i×ln(i)=ln(x)-----(1)
    Now as we know e^iπ=-1
    And(-1)=i^2
    e^iπ=i^2 then take ln both sides then (iπ)=2ln(i)
    Which equals (iπ)/2=ln(i)------(2)
    Now put (2) in (1)=
    {ln (i)=iπ/2}
    1/i×iπ/2=ln(x)====
    π/2=ln(x) so
    e^π/2=x
    I hope this can also be a solution...☺

  • @noodleplexium5953
    @noodleplexium5953 3 роки тому

    The thumbnail has tortured me after a tough maths test. Stop

  • @ThaRealChuckD
    @ThaRealChuckD 5 років тому

    Good one!

  • @meerable
    @meerable Рік тому

    As far as I know, the transition from sqrt to power imposes restrictions on the argument. And here it is observed?

  • @ErwinSalasErwin
    @ErwinSalasErwin 3 роки тому

    Professor, I have a question, is it possible to have a real number to the power of a matrix?

  • @gauravbhalerao7420
    @gauravbhalerao7420 3 роки тому

    My mind is blown and my curiosity satisfied

  • @leonkim418
    @leonkim418 5 років тому

    I bet you are great teacher

  • @hamsack981
    @hamsack981 3 роки тому

    I don't even think about this kind of stuff. It's crazy that some dude was like, oh there's an i'th root of I, let's solve what it is...

  • @RaspingBubbles6
    @RaspingBubbles6 6 років тому +6

    How much different is it for a question such as i^(a+bi) or i^(rcisArg)

    • @yuvraj7214
      @yuvraj7214 6 років тому

      RaspingBubbles6 you can distribut as i^a • i^bi, then write i^bi as i^i^b the write i^i as e to the π/2, there you have it.

  • @Fredson167
    @Fredson167 4 роки тому +6

    00:32 Lost my concentration there

  • @ianboard3555
    @ianboard3555 3 роки тому

    I've given this as an interview question (I'm an EE) - it's easy if you just work your way through it.

  • @General12th
    @General12th 6 років тому

    *SO GOOD*

  • @Dav753
    @Dav753 6 місяців тому

    How or why can you plug in that e to the negative pi halves in the place of i to the i?

  • @_DD_15
    @_DD_15 5 років тому +1

    Why did you multiply by i over i? You could have substituted e to the i pi/2 as first step. And then cancel out the i and get the result in 2 steps. :)

  • @nucderpuck
    @nucderpuck 3 роки тому

    Always being on top is like having only real numbers. Broaden your horizon!

  • @nosirrahx
    @nosirrahx 3 роки тому

    If I have learned anything from this channel it is that if you something strange to i, e and/or pi are going to pop out of the equation.

  • @jeim376
    @jeim376 4 роки тому

    The greatest crossover in history.