Complex Numbers (part 1)

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  • Опубліковано 20 січ 2025

КОМЕНТАРІ • 232

  • @TheAlexmercer360batmanfan
    @TheAlexmercer360batmanfan 10 років тому +68

    This guy really knows how to teach,as in,how to get things inside the most clueless of the heads,I would wager these videos are better than most local tutors you would find in US,some would charge huge money for the iinfo contained in this tiny vid,so Mr.Khan,you have our most dear thanks :)

  • @stephentoenjes108
    @stephentoenjes108 10 років тому +113

    The most soothing voice on the web.

    • @peihu3201
      @peihu3201 8 років тому +2

      ikr

    • @shripriyaramanujam8711
      @shripriyaramanujam8711 7 років тому +2

      Well, second most soothing voice on the Web. There are video recordings of _The Joy of Painting_ by Bob Ross

    • @wiz9203
      @wiz9203 6 років тому +2

      Most scary voice 😨😨😨😨😨😬😬😱😱

  • @imapabdou2503
    @imapabdou2503 7 років тому +320

    Stop scrolling down, and focus on the video.

    • @hindaomar2329
      @hindaomar2329 7 років тому +9

      BENACHOUR Abdou ok sorry

    • @thyduck7542
      @thyduck7542 6 років тому +4

      My bad

    • @Teal_.
      @Teal_. 5 років тому +1

      yea my bad, thanks for looking out for me

    • @numbersletters2920
      @numbersletters2920 5 років тому +1

      1➗♻️💤🖼🎼❄️😢math classes in university establish myself as career ready.

    • @maramkh1423
      @maramkh1423 3 роки тому

      Ok thanks for the warning lol

  • @talzO9
    @talzO9 9 років тому +167

    I wish Khan would re-do these videos in higher quality so they were easier to look at. Still great though!

    • @pebble2259
      @pebble2259 7 років тому +1

      Is it possible this is a dupe channel fishing for likes?

    • @timtams_6
      @timtams_6 5 років тому +3

      @@pebble2259 It's a video from 2008. What would you expect?

  • @remedyzipcode4603
    @remedyzipcode4603 9 років тому +17

    My teacher sucks so bad at teaching geometry im glad you do these videos to help people like me

  • @harderhscmaths
    @harderhscmaths 12 років тому +1

    Thank you Sal. You are an inspiration. Through your help I have begun my UA-cam videos.
    It was a bit daunting at first but now I am getting into the swing of it. I have watched your style and your relaxed manner has helped enormously. I don't worry as much when I make a mistake and this makes it more enjoyable in the presentation. I believe that we are providing great opportunities for students wh cannot afford textbooks or are too far away from a school. Once again thank you. John Kinny-Lewis

  • @yakmuck
    @yakmuck 16 років тому

    great videos. College has no mercy for us math deficient distance learning students. These vids are a good resource for the lost.

  • @ApoorvaV
    @ApoorvaV 9 років тому +15

    I love Khan academy!!!!! Thank you so much for helping me.

  • @alexbat007
    @alexbat007 11 років тому +11

    If only all people could teach like this with this sort of homework!

  • @0riginalrick
    @0riginalrick 14 років тому +1

    Thank you so much. It makes me wonder why math books and math teachers make it seem so difficult. What I couldn't understand after 3 hours of studying from my mathbook, I now do understand in under 20 minutes watching your video.

  • @25911454
    @25911454 14 років тому

    what my tutor coulndnt teach me in a week............sir,u taught me in 10 mins.............thnk u so mch sir......i will surely get gud mrks

  • @jacobnathanielbutler
    @jacobnathanielbutler 11 років тому +1

    I could save a shitload of money just staying home and watching these videos all day, I would definitely learn more. To bad I have to pay thousands of dollars for a piece of paper with my name on it....

  • @victornavarro4285
    @victornavarro4285 11 років тому +1

    love these kind of videos they explain and make things clear!

    • @franklinmaldonado1949
      @franklinmaldonado1949 5 років тому +1

      Victor Navarro is greatly help me out and have fun in Florida for the best for🕶️👓🕳️🕳️👢👒

  • @MrAndySickness
    @MrAndySickness 12 років тому

    Okay so I actually enjoy math to some extent, but this chapter ticks me off.
    And you just made it fun and easy to understand and it was funny. c:
    The dimension thing really helped haha. Thanks dude.

  • @steven1234554321
    @steven1234554321 12 років тому

    Thanks for the lesson! And for getting me to look up and learn the word monotenous! Such a sick word!

  • @dhritisuresh8131
    @dhritisuresh8131 5 років тому

    'I dont wanna confuse you' 1:52
    No Sal, you're helping me with my degree

  • @paddaguduru
    @paddaguduru 5 років тому +1

    Sal's voice is ASMR
    New Bob Ross

  • @deepaksompurkar2946
    @deepaksompurkar2946 7 років тому

    namaste and thanks for enriching worlds knowledge through your endeavour

  • @mehdijalali2874
    @mehdijalali2874 8 років тому +3

    We thank for your nice activity of the UA-cam

  • @كورةبلس1-ث1ظ
    @كورةبلس1-ث1ظ 7 років тому +11

    I am the son of wounded Syria. We lost our homeland and we still want to learn ... Syria Damascus

  • @alansmithee419
    @alansmithee419 6 років тому +4

    2:00. I get annoyed at this too. Imaginary is a terrible name. They're just as valid as any other number. They're just different.

    • @dingdong3021
      @dingdong3021 3 роки тому

      Then call them anything you want idiot.

  • @thetrillchemist8555
    @thetrillchemist8555 10 років тому

    Great explanation totally makes sense! I'm happy to know what I have coming this August !

  • @DumbNinjaDude
    @DumbNinjaDude 5 років тому

    I had an interesting thought; if you graph the y axis vertically and the x axis horizontally, could you then use the “imaginary” axis perpendicular to that x,y plane and generate functions in all 3 dimensions?

  • @Underdisc
    @Underdisc 12 років тому

    I have a suggestion for you Khan. You should make a playlists that separate the curriculum from multiple subjects. One should have all of the Geometry Curriculum, Algebra 2 Curriculum. Pre-Calculus Curriculum, and etc. If you do that, I can skip two years in mathematics.

  • @danielingvarsson3029
    @danielingvarsson3029 10 років тому +9

    It works if you fast forward few seconds.

  • @estarossa1847
    @estarossa1847 6 років тому

    I appreciator your explanation skills

  • @labmem004
    @labmem004 8 років тому

    Thank you for that good lesson. Much love!

  • @muranvya
    @muranvya 15 років тому

    yo, Sal, u saved me in calculus II, u do
    Calculus III as well? I'm saveeeeed again. U have no idea how happy i was to hear ur voice

  • @thelastvampirehunter
    @thelastvampirehunter 13 років тому

    This video helped out a lot, thank you!

  • @Visualizingmathandphysics
    @Visualizingmathandphysics 12 років тому

    So just as there is East, West, North and South,
    In maths, there is
    1,i,-1 & -i.
    Hope this helps
    Binnoy.

  • @danny3640
    @danny3640 5 років тому

    In 1:25 if we defined I as -1 and we squared it wouldn't it become 1?

    • @negarv6093
      @negarv6093 5 років тому +1

      Im pretty late but I^2 is defined as -1 not I

  • @DecoyProductions
    @DecoyProductions 6 років тому

    These videos need to be rerecorded, its been 10 years Sal!

  • @jerome1470
    @jerome1470 13 років тому

    Thank you for this video! It helped me understand much better a hell lot! :)

  • @suprgx
    @suprgx Рік тому +1

    Legend

  • @shallowcoder1
    @shallowcoder1 11 років тому +1

    now why can't all teachers be this good?

  • @sauri2005
    @sauri2005 14 років тому

    thank you so much for this. really easy to understand. i hope you were my calc teacher. i was wondering if you have any videos for sinusoidal steady state analysis

  • @MariaDiaz-tg5cn
    @MariaDiaz-tg5cn 12 років тому

    muy buena tu esplicacion, a pesar de que no hablo tu idioma, entendi, gracias!

  • @mollyalfred7099
    @mollyalfred7099 5 років тому

    CAPE Inte. Math on Monday... Thanks for the videos!

  • @lawal211
    @lawal211 12 років тому

    Thank you so much. This was a lot of help.

  • @Gogargoat
    @Gogargoat 11 років тому

    So a real number is magnitude, and the imaginary part of a complex number is also magnitude, but is orthogonal to the real magnitude?
    When you multiply by an imaginary part, you also rotate the vector 90 degrees pushing it into the other dimension?
    I'm not sure exactly how to say it, but am i understanding this correctly?

    • @WilliamFordRoom340
      @WilliamFordRoom340 10 років тому

      Gogargoat Yes. If you graph a quadratic equation it makes a parabola; however, the graph of the complex solutions to that same quadratic equation will form a parabola perpendicular to the Cartesian plane.

  • @dharma6662013
    @dharma6662013 9 років тому

    This is a great video, but be careful. i^2 = - 1 gives two possible definitions for i because i^2 = - 1 and (- i)^2 = - 1. The custom is to choose i = +\sqrt(- 1). There are really two models for the complex numbers. They are automorphic under conjugation z --> z*.

  • @protoname_
    @protoname_ 12 років тому

    Thanks so much! I owe you tons!

  • @alansmithee419
    @alansmithee419 6 років тому +1

    Wait. Is i bigger than -i? Is 2i bigger than i? Is there no concept of 'bigger' when it comes to these numbers? I suppose they're all 0+ni meaning they are all 0 with some other value that isn't really 0 but is on the real plane? But then you could say that all real numbers are 0i+n, making my point meaningless. Is it that they are bigger only on the imaginary axis and that real numbers get bigger on the real axis?

    • @douglasstrother6584
      @douglasstrother6584 5 років тому

      Consider the modulus of a complex number as its size:
      mathworld.wolfram.com/ComplexModulus.html

  • @mariabrader461
    @mariabrader461 6 років тому

    thank you! probably saved my grade.

  • @Visualizingmathandphysics
    @Visualizingmathandphysics 12 років тому

    Complex numbers actually indicate rotation.
    i = rotation by 90 degrees.
    i^2 = rotation by 180 degrees = -1 = negative of that number.
    .
    i^3= rotation by 270 degrees = -i
    i^4 = rotation by 360 degrees =1.
    Rotation by 360 degrees brings the object back to the same position.
    Take any object in your hand and rotate it by 90 degrees 4 times. You will see that it comes back to as it was before rotation.
    There is a whole video dedicated to complex numbers on my channel, if you wish
    Binnoy

  • @jhonchavez3124
    @jhonchavez3124 9 років тому

    So all complex numbers do is turn the number into negative or positive?

    • @qbwkp
      @qbwkp 9 років тому

      No, a complex number consists of a real and a imaginary part
      Bi can also be a complex nimber since the real number can = 0, so bi+0 is still a complex number and vice versa

  • @LesIsMoreFilms
    @LesIsMoreFilms 11 років тому +1

    This is all fine and dandy...but what does this have to do with Batman?

  • @moctezuma696
    @moctezuma696 10 років тому +7

    Thanks for that... Mr Khan, could you please tell me what software / e-pen / digital pen you are using. I am looking for user-friendly delivery platform. Thanks in anticipation. Moctezuma

  • @khodorhajj8386
    @khodorhajj8386 4 роки тому

    Very nice lesson

  • @energie9966
    @energie9966 9 років тому

    nice videos. i have another different powerful explanation for complex numbers

  • @Guitare_picking
    @Guitare_picking 12 років тому

    would -3i also be a solution of (-9)^(1/2)? because if I square -3i I have -9

  • @pussybag6417
    @pussybag6417 12 років тому

    You explained this so much better than my college professor ha

  • @richardaiwe1542
    @richardaiwe1542 7 років тому +1

    Nice work !! Wish i found dis earlier.

  • @rajcatchem7942
    @rajcatchem7942 10 років тому +1

    Find all complex numbers z satisfying z5 = 1 + 2j. How many complex
    numbers satisfy this equation?

  • @ChuuliviaHye
    @ChuuliviaHye 11 років тому

    Wow. You explain this way better than my teacher xD

  • @Visualizingmathandphysics
    @Visualizingmathandphysics 12 років тому

    Complex plane was invented to measure rotation, just as a normal x-y plane is used to measure change in size, length, distance etc.
    Binnoy
    Visualizing Maths
    A book beyond Formulas

  • @luckylove72
    @luckylove72 12 років тому

    I don't get this thing. In book CN i defined as ordered pair (x,y) x and y real. Then it defines i as (0,1). It also defines Re(z)=x and Im(z)=y. Then addition and multiplication ....then book writes (x,0)=x plz explain this. I figure out this only Re(z=(x,0))=x But how (x,0)=x??. Soon my exams are from 23rd

  • @Nemanoid
    @Nemanoid 6 років тому

    what program does he use to explain this?

  • @lwreltteratgmail
    @lwreltteratgmail 12 років тому

    why is this in the first half of algebra? i personally dont have a problem with that but i dont understand this kind of order...

  • @Luxcium
    @Luxcium 7 років тому

    This video is so nice but I am used to a so high level of quality now so the lack of pop filter annoys me so much but hey dont worry for me its still a great teacher and a nice video

  • @sangeetanurag6537
    @sangeetanurag6537 11 років тому

    compute
    z= cosa+sina+i(sina-cosa)
    after findind
    t*=a-pi/4
    then what i will do and what will z+?

  • @lucyandljk
    @lucyandljk 13 років тому

    Watching a productive 10 minute video instead of going to a 50 min lecture :D at home while eating subway :D

  • @Harry0Ron0Hermione
    @Harry0Ron0Hermione 16 років тому

    Is this for high lvls?

  • @frostshadow5
    @frostshadow5 13 років тому

    when he subtracted z1 - z2 why did he get (a-c) PLUS (b-id)i , emphasise on the plus linking the two there

  • @shiza223
    @shiza223 14 років тому

    you are a hero!!!

  • @fireballBTF69
    @fireballBTF69 11 років тому

    wouldnt root -9 be 9i? since root -1 is i??? im confused

  • @feminineessence2007
    @feminineessence2007 7 років тому

    At which grade do u usually start learning this?

  • @GndmMkv
    @GndmMkv 14 років тому

    i heard that imaginary numbers were to be used in eletricity. respond to me if im right beacuse i dont really remember

  • @onomaeponumo4085
    @onomaeponumo4085 6 років тому

    just one question but you say i^2=-1 and i get it but then you say sqr(-9)=3i why not 3i^2

    • @alansmithee419
      @alansmithee419 6 років тому

      Because that would equal -9, not root( -9), as shown early in this video.
      Edit: actually 3i^2 would be -3. (3i)^2 is -9

  • @v3le
    @v3le 7 років тому

    1:40 I came to the exact point and asked: do the negative numbers really exist ???

  • @harderhscmaths
    @harderhscmaths 12 років тому +1

    I also do complex numbers from past exam papers.

  • @ethansegat9713
    @ethansegat9713 7 років тому +1

    I am new to this. Why does i^2 = -1?

    • @BiscuitZombies
      @BiscuitZombies 7 років тому +2

      Ethan Segat because i = the square root of 1
      So if you square both sides, i^2 = -1

    • @Suggy08
      @Suggy08 6 років тому

      It just is. It's like saying why are bananas yellow

    • @alansmithee419
      @alansmithee419 6 років тому

      @@Suggy08 because its evolutionarily good for them

  • @alZiiHardstylez
    @alZiiHardstylez 14 років тому

    Looking up some hardstyle and I've reached exactly what I had to complete for my tutor.
    Fate?

  • @macmike76
    @macmike76 13 років тому

    thanks, really helpfull and with subs

  • @alijahhodgson390
    @alijahhodgson390 6 років тому

    For those discussing the quality, youtube videos actually slowly degrade in quality over the years and develop some artifacting, which has been proven on a number of occasions. This is most likely caused by the video files being moved from server to server, compressed, copied, or otherwise disturbed over the years since they were initially uploaded.

  • @mosamariamathews3217
    @mosamariamathews3217 7 років тому

    thank you so much i understand much better

  • @jirosei8
    @jirosei8 12 років тому

    what about linear vector spaces?

    • @franklinmaldonado1949
      @franklinmaldonado1949 5 років тому

      jirosei8 is greatly help you 😎🧘 👤👤 👤🗣️👤👤👤 👤🗣️ is greatly help me with this matter is greatly help you with

  • @MrMcVilla
    @MrMcVilla 11 років тому

    No, root -9 would be 3i. -9= 9i^2, so root -9 is root 9 multiplied by root i^2, which is 3i

  • @JoeClawsy
    @JoeClawsy 15 років тому

    @k0du123
    It's used in electronics and fluid mechanics

  • @josh-bond97
    @josh-bond97 11 років тому +1

    Complex numbers........... they sure got that name right

  • @demisous
    @demisous 15 років тому

    your the best :)

  • @issunRyuBlackBelt
    @issunRyuBlackBelt 13 років тому

    Found this right after my test. Of course.

  • @SamiWaters5634
    @SamiWaters5634 11 років тому

    very helpful for review! thanks!

  • @nipunrathi6459
    @nipunrathi6459 7 років тому

    can you solve this one
    α+iβ=1/a-ib complex number to prove (α^2+β^2)(a^2+b^2)=1

    • @Reyan09
      @Reyan09 7 років тому

      Nipun Rathi use the trigonometric formulas.

  • @its.freyja
    @its.freyja 13 років тому

    @MilitaryMan006 It is 0.707 + 0.707i, or √(1/2) + √(1/2) i

  • @ANonyMouse627
    @ANonyMouse627 7 років тому

    Skip to 4:18

  • @mynameisnotgirl8184
    @mynameisnotgirl8184 8 років тому +1

    I wish the writing was consistent. Some 2's looked like 7s, equal signs looked like C's and i's looked like L's.

  • @toolbass24
    @toolbass24 14 років тому

    Ty Sal. U sound like the guy from super Mario frustration

  • @mmSeven77
    @mmSeven77 14 років тому

    @caseywtw The imaginary number i is defined solely by the property that its square is −1

  • @XDGB97DX
    @XDGB97DX 12 років тому

    ahh thank you my friend for making that clear to me =)

  • @Foreveralonecuuuh
    @Foreveralonecuuuh 9 років тому +10

    I'm so confused

  • @Perrydiculous
    @Perrydiculous 10 років тому +6

    Why doesn't this work? I have to go to my calculus resit in an hour :P

    • @reatleatmcpagani4997
      @reatleatmcpagani4997 7 років тому +1

      when you see this comment from 3 years ago xPPPP
      so how did you do the resit?

  • @braidznplaitz
    @braidznplaitz 12 років тому

    u may check his videos in other languages as well

  • @AA-dd6nr
    @AA-dd6nr 6 років тому

    I think there is something odd with his equation on subtraction

  • @Magmatwister
    @Magmatwister 12 років тому

    my maths teacher does this sometimes...problem is there are some really smart people in my class so she get's away with it alot of the time...I mean... I get it.. eventually after much difficulty, but It doesn't need to be so hard - _ -

  • @NateMan58
    @NateMan58 15 років тому

    Sweet thanks mate!

  • @kmogilevsky
    @kmogilevsky 10 років тому

    The video doesn't work :-(

  • @martmelee
    @martmelee 14 років тому

    wow you got some skills with the mouse...LOL

  • @Chowmeingeejah
    @Chowmeingeejah 13 років тому

    cAn someone plz tell meee wat iz: a + bi ?

  • @Chowmeingeejah
    @Chowmeingeejah 13 років тому

    @IAMMATSUDA have you never heard of short hand informal writing