Imaginary Numbers Are Real [Part 2: A Little History]

Ғылым және технология

Want to learn more or teach this series? Check out the Imaginary Numbers are Real Workbook: www.welchlabs.com/resources.
Imaginary numbers are not some wild invention, they are the deep and natural result of extending our number system. Imaginary numbers are all about the discovery of numbers existing not in one dimension along the number line, but in full two dimensional space. Accepting this not only gives us more rich and complete mathematics, but also unlocks a ridiculous amount of very real, very tangible problems in science and engineering.
Part 1: Introduction
Part 2: A Little History
Part 3: Cardan's Problem
Part 4: Bombelli's Solution
Part 5: Numbers are Two Dimensional
Part 6: The Complex Plane
Part 7: Complex Multiplication
Part 8: Math Wizardry
Part 9: Closure
Part 10: Complex Functions
Part 11: Wandering in Four Dimensions
Part 12: Riemann's Solution
Part 13: Riemann Surfaces
Part 2 especially owes a debt to Paul Nahin's excellent book: An Imaginary Tale: The Story of sqrt(-1). Nahin presents a very thorough account of the development of imaginary numbers, which was invaluable in creating this series.

Пікірлер: 977

  • @amohogride3739
    @amohogride37395 жыл бұрын

    Imagine a mathematician running around the street carrying a sheet of questions finding an opponent. This is basically Pokemon

  • @thegecko1992

    @thegecko1992

    5 жыл бұрын

    SQUIREROOTLE, I CHOOSE YOU

  • @sawada_.

    @sawada_.

    5 жыл бұрын

    @@thegecko1992 SquareRootle*

  • @stonetop

    @stonetop

    4 жыл бұрын

    It uses derivative on e^x, it wasn't very effective

  • @megugu2155

    @megugu2155

    3 жыл бұрын

    Millenium Problems gon be like Arceus

  • @savagenovelist2983

    @savagenovelist2983

    3 жыл бұрын

    No, it would be more like a Pokemon Gym. You go to a designated Math Dueling place and somebody gets you into the next match for your skill level.

  • @xxnotmuchxx
    @xxnotmuchxx7 жыл бұрын

    Mathematicians should continue to have duels. That sounds pretty cool.

  • @ssunvenomcast4975

    @ssunvenomcast4975

    7 жыл бұрын

    Yea!!

  • @rich1051414

    @rich1051414

    7 жыл бұрын

    It actually caused a lot of groundbreaking mathematics to be lost to time, due to greed. It basically caused proprietary formulas so the mathematicians could keep winning duels.

  • @SlaveToMyStomach

    @SlaveToMyStomach

    7 жыл бұрын

    Kind of like how patents are used today. Not winning duels but ... profit!

  • @gabrob27

    @gabrob27

    7 жыл бұрын

    Please consider revising your pronunciation of Italian surnames - video is nice but Tartaglia and Del Ferro are suffering in their deathbeds.. :)

  • @SiddharthBhatt24

    @SiddharthBhatt24

    7 жыл бұрын

    Ever heard of MIT Integration Bee? It's basically a math duel tournament.

  • @anarki777
    @anarki7778 жыл бұрын

    Holy shit. Math duels? Are you serious? That's pretty hilarious.

  • @Nothing_serious

    @Nothing_serious

    7 жыл бұрын

    anarki777 It's still a thing. There's even math Olympic. I think one of Numberphile's host is a champion.

  • @steelep5623

    @steelep5623

    7 жыл бұрын

    anarki777 Expecto Numerum!

  • @msDanielp369

    @msDanielp369

    5 жыл бұрын

    yeah they were actually math freestyle battles they were pretty dope. only XVIth century kids will remember 😫👌🏻🔥

  • @PsyQoBoy

    @PsyQoBoy

    5 жыл бұрын

    The Romans did maths duels and the Egyptians played duel monsters you do the maths!

  • @timmy18135

    @timmy18135

    4 жыл бұрын

    Engard

  • @Technomancr
    @Technomancr8 жыл бұрын

    Why did you abandon calling them lateral numbers?

  • @WelchLabsVideo

    @WelchLabsVideo

    8 жыл бұрын

    +Anthony Trupiano Yeah - good point. It's just a question of how much I should break with convention here - lateral makes way more sense, but most people don't know what you're talking about when you say "lateral number".

  • @KManAbout

    @KManAbout

    8 жыл бұрын

    +Welch Labs I thought they are called complex numbers

  • @KManAbout

    @KManAbout

    8 жыл бұрын

    ***** but a+b = i is impossible because no real numbers exist that are equal to i. if you mean that complex numbers included any combination of real numbers with i then I understand. for example if you mean 6+ 2i is a complex number but not 6 or 6i.

  • @KManAbout

    @KManAbout

    8 жыл бұрын

    okay cool

  • @MamboBean343

    @MamboBean343

    7 жыл бұрын

    Soldier ˙ Wait! The complex numbers include real numbers like √2 and imaginary numbers like i and 6i. However, like many groups of numbers, the term "complex number" may only refer to the non-real, non-strictly imaginary numbers (a+bi, where a and b are real)

  • @ryannelson768
    @ryannelson7687 жыл бұрын

    this is a KZread gold mine

  • @anonymoustraveller2254

    @anonymoustraveller2254

    6 жыл бұрын

    Ryan Nelson yeah

  • @HDitzzDH
    @HDitzzDH3 жыл бұрын

    3:35 That is not quite correct, the current definition of the square root only accounts for the positive number whose square is the number inside the square root, the only time you inlude +/- is when you're solving an equation. The square root itself is only defined for one positive number.

  • @pradyunmore6727

    @pradyunmore6727

    3 жыл бұрын

    @ GZA yes you are correct. I don't know why many people in the comments haven't pointed this out!

  • @user-cj2zh5pr3k

    @user-cj2zh5pr3k

    3 жыл бұрын

    I didnt know some ppl think root9=-3

  • @theawezome6699

    @theawezome6699

    3 жыл бұрын

    This is only for notation purposes, ie it is the pricipal root.

  • @user-od8gb9ny7q

    @user-od8gb9ny7q

    3 жыл бұрын

    bruh you've said it a month before me so sad:)

  • @bdbd7045

    @bdbd7045

    3 жыл бұрын

    I was looking for this comment!!

  • @wiredelectrosphere
    @wiredelectrosphere5 жыл бұрын

    This math duel thing is presented like you can make an anime out of it

  • @maxif4950

    @maxif4950

    4 жыл бұрын

    You watched dr stone?

  • @cristaldark4228

    @cristaldark4228

    4 жыл бұрын

    Yesssss! !!

  • @yousiffaris696

    @yousiffaris696

    4 жыл бұрын

    I have been searching for squaring numbers animation or explanation on x,y and I still haven’t found yet all of what I find is 3 squared = 9 and bla bla bla😤

  • @yareyaredonut

    @yareyaredonut

    3 жыл бұрын

    Actually that's just what we do in exams

  • @kinokonyan

    @kinokonyan

    3 жыл бұрын

    mmm yes

  • @HolahkuTaigiTWFormosanDiplomat
    @HolahkuTaigiTWFormosanDiplomat2 жыл бұрын

    So that is how...Vertassium got the term of math duel?

  • @takeuchi5760

    @takeuchi5760

    2 жыл бұрын

    Yeah, looks like he copied these videos.

  • @rabeebibrat1805
    @rabeebibrat18053 жыл бұрын

    A HUGE thumbs up for the historical context, which math texts don't provide. Interesting series! Keep up the good work.

  • @ExperimentarEnCasa
    @ExperimentarEnCasa8 жыл бұрын

    beautiful videos! LOVE THEM

  • @MilloSteve

    @MilloSteve

    3 жыл бұрын

    Tu canal es una mierda ahora

  • @daver72016

    @daver72016

    3 жыл бұрын

    This is just long winded CRAP, because there ISN'T one definitive correct answer to this !

  • @daesmua

    @daesmua

    3 жыл бұрын

    @@MilloSteve Jajjaja si

  • @alesdiaz1177

    @alesdiaz1177

    3 жыл бұрын

    @@MilloSteve Con lo mitico que era el canal en su momento

  • @Maceta444
    @Maceta4443 жыл бұрын

    Nerds before: "I just murdered someone in a math duel and I'm on the 30th page solving this single equation" Nerds now: "Why this python code not work"

  • @julesverne6287
    @julesverne62878 жыл бұрын

    How long did it take to cut out all the continents of the world?

  • @WelchLabsVideo

    @WelchLabsVideo

    8 жыл бұрын

    +Lorcan O'Brien Good question - that didn't actually take too long. Shooting with camera motion, however, takes FOREVER.

  • @liquidmodernitytasteslikeu2855

    @liquidmodernitytasteslikeu2855

    5 жыл бұрын

    Nice profile picture

  • @beta5770
    @beta57708 жыл бұрын

    This is gold. Never have I seen better VFX used in presentations for such a basic topic.

  • @sajjadulhaq8914
    @sajjadulhaq89147 жыл бұрын

    Words are just not enough to explain how awesome these series are. Only true mathematician can understand that how difficult it is to prepare such lectures. I have been searching for such kind of study from many years. I am truly great-full for this series.

  • @humbledb4jesus

    @humbledb4jesus

    11 ай бұрын

    3920506-13232-39850-23...422-4670-74!!!!! translation: only true mathematicians speak in numbers....

  • @trulyUnAssuming
    @trulyUnAssuming8 жыл бұрын

    sqr(9) = 3 and sqr(9) != -3. At least in the usual definition. Since you define the squareroot as the inverse function of f: [0, infinity] -> [0, infinity]; x -> x². But the solution to x²=9 is x=+/-sqr(9)=+/-3

  • @user-so5zf4js9v

    @user-so5zf4js9v

    5 жыл бұрын

    Glad someone pointed it out.

  • @danielfloresretamal2471

    @danielfloresretamal2471

    4 жыл бұрын

    the square root of a positive number (or 0) is unique and always positive (or 0)

  • @dabzdavid2378

    @dabzdavid2378

    4 жыл бұрын

    @@danielfloresretamal2471 unique and nonnegative

  • @danielfloresretamal2471

    @danielfloresretamal2471

    4 жыл бұрын

    @@dabzdavid2378 that summarizes it

  • @Trucmuch

    @Trucmuch

    4 жыл бұрын

    You guys get that by your own definition i is not the square root of -1.

  • @robertwilsoniii2048
    @robertwilsoniii20487 жыл бұрын

    This playlist is awesome!! I love learning the history of the math while learning the math! This is how it should be taught in general.

  • @Fo2shstein
    @Fo2shstein8 жыл бұрын

    Just wanted to pop in & compliment the effort in these videos, love the math/history/stickman commentary combo. Hope to see more!

  • @alexanderherbertkurz
    @alexanderherbertkurz2 жыл бұрын

    I love the way this mixes history and math. And handwriting and computer animation. Absolutely brilliant. Should be one of my favourite math videos now. Added: It is actually almost addictive ... I am going to watch the rest of the videos even though I know the stuff.

  • @samkoesnadi
    @samkoesnadi7 жыл бұрын

    This is very very useful. I like it a lot. Thank you for your hardwork on this video!

  • @WelchLabsVideo

    @WelchLabsVideo

    7 жыл бұрын

    Thanks for watching!

  • @yashwantmente9293
    @yashwantmente92933 жыл бұрын

    That's how maths is supposed to be taught, combining it with history. Most of the times we don't even know why certain things came into existence, and everything seems like fiction deduced just for students to write exams. Everything makes perfect sense now.

  • @ASLUHLUHCE

    @ASLUHLUHCE

    2 жыл бұрын

    Same with science

  • @geekonomist

    @geekonomist

    Жыл бұрын

    Math is supposed to integrate arithmetic, algebra, calculus, history, and LOGIC. Show me any other dimension beyond the 3 we know of; use a measuring tape while doing so. There are no results from the sqrt of a negative. Once you integrate this, you can add to the math history lesson that men have often fallen prey to ridiculous contradictions as a matter of popular ideas. IE God, the Minimum Wage, Quantitative Easing, Altruism.... and the square root of -1

  • @clips9294
    @clips92942 жыл бұрын

    Just watched Veritasium

  • @Algebrodadio
    @Algebrodadio7 жыл бұрын

    Bonus for deriving the quadratic formula in like 2 seconds.

  • @EDUARDO12348
    @EDUARDO123487 жыл бұрын

    So glad you made these videos...! you're like a master chef here, adding just the right amount of history spice.

  • @Qebton
    @Qebton8 жыл бұрын

    this video is so underrated man its so freaking amazing i'm going to show it to everyone i know

  • @manjunathnavalgund7266
    @manjunathnavalgund72667 жыл бұрын

    wow....this series is addictive....I am binge revising my school algebra

  • @mistyseas

    @mistyseas

    4 жыл бұрын

    Manjunath Navalgund I hate math and I like this for some reason

  • @strangelongcat7830
    @strangelongcat78306 жыл бұрын

    I'm literally in love with this channel

  • @proyc95
    @proyc957 жыл бұрын

    amazing info and props for explaining all the details. gives great insight into how maths develops. you guys are doing a great stuff !

  • @alacer8878
    @alacer887811 ай бұрын

    You make math interesting for a reason so so many math curriculums fail to see. You include the context. It's one thing having formulas thrown at me, and the rules for solving them, and being told to memorize. It's another thing entirely to find out why those formulas were made to begin with.

  • @WelchLabsVideo

    @WelchLabsVideo

    11 ай бұрын

    Amen!!

  • @alacer8878

    @alacer8878

    11 ай бұрын

    @WelchLabsVideo I want you to know I found you through your atom bomb videos. I'd also like you to know the quality of your videos holds up 6 years later. You should be very very proud of yourself mister professor dad.

  • @ojkwame

    @ojkwame

    10 ай бұрын

    @@WelchLabsVideoPlease is your info from history of mathematics by Dan Burton ? If not then can you share your resource(s)?

  • @tankmaster9212
    @tankmaster92124 жыл бұрын

    LOVE THE FACT THAT YOU BRING MATH'S TO LIVE AND VISUALIZABLE

  • @simplecastic
    @simplecastic7 жыл бұрын

    you make algebra look fun and love the history i never knew

  • @angelabakloyvovtchaikovsky1609

    @angelabakloyvovtchaikovsky1609

    3 жыл бұрын

    Math is useless in real life

  • @kevingarner7231
    @kevingarner72318 жыл бұрын

    Couldn't stop with the first video. Can't stop with the second. Gotta see the third!

  • @5i1v3rStorm
    @5i1v3rStorm5 жыл бұрын

    1:40 mouth open in wonder! Thank you so much for going through the trouble of bringing me stuff closer I could have learned at school but hadn't paid attention (or had bad teachers, I suppose)!

  • @WoLF42x
    @WoLF42x8 жыл бұрын

    The square root of 9 is strictly 3. When approaching x^2 = 9, only when you square root do you get the plus-minus in front of the positive root to indicate +-3

  • @pipolwes000

    @pipolwes000

    8 жыл бұрын

    +WoLF42 No. Both 3 and -3 are square roots of 9, since 3*3 = 9 and (-3)*(-3) = (-1)*(-1)*(3)*(3) = 3*3 = 9. Depending on what problem you are solving, different solutions will make sense but both positive and negative values are valid square roots when you have no other constraints.

  • @sagarprasad1436

    @sagarprasad1436

    6 жыл бұрын

    pipolwes000 this is the general mistake we all make..i know -3 ×-3 is 9 but when taking square root only positive values appers...if u try to use the -ve values then there are ways to prove 1=2 which is not true...i dont know how much maths u have studied and i will also not tell u to believe me but try to gather information by yourself and i assure u 500% u will believe what i am trying to tell u

  • @sagarprasad1436

    @sagarprasad1436

    6 жыл бұрын

    WoLF42 glad to find someone identified the mistake👍

  • @kilianmelcher3811

    @kilianmelcher3811

    6 жыл бұрын

    Yesss, you are right!

  • @junhaowang1834

    @junhaowang1834

    6 жыл бұрын

    pipolwes000 Principle square root is a function, you can't get two answers!

  • @TonyAKA30
    @TonyAKA308 жыл бұрын

    Math has never been this interesting!

  • @EduardoHerrera-fr6bd

    @EduardoHerrera-fr6bd

    5 жыл бұрын

    But it's interesting to answer your comment.

  • @zlatan4467

    @zlatan4467

    3 жыл бұрын

    @@EduardoHerrera-fr6bd it's interesting too reply yours too.

  • @DarkGourmand

    @DarkGourmand

    2 жыл бұрын

    @@zlatan4467 yours too

  • @agustinbs
    @agustinbs8 жыл бұрын

    Amazing!! you simply know very well how to explain something in a way we can connect the dots on the basics we know to topics that are very unintuitive. the example of negative numbers and the negative apples is an amazing way to finally make sens about imaginary numbers

  • @nabeelakhter5799
    @nabeelakhter57997 жыл бұрын

    One of the best video I have seen on KZread,It's awesome .Thanks WelchLabs

  • @WelchLabsVideo

    @WelchLabsVideo

    7 жыл бұрын

    Thank you!

  • @dactylntrochee
    @dactylntrochee4 жыл бұрын

    Whoa! This is a shocker to me, right from the start. I was no great student in 1965, but numbers always came easily to me, and I remember a happy 98% on our (New York) statewide final exam in algebra. My takeaway from that time is that quadratics were solved on inspection, and that there was no mechanism to find the roots. The concept of a universal formula, as I recall, was actively denied. I wonder if this is senility! What could possibly have made me think that? Well, it's a delight to see it now, all these years later.

  • @tifforo1
    @tifforo17 жыл бұрын

    x^3 = 15x + 4 has three real-valued solutions, the simplest of which is 4. 4^3 = 64. 15*4 + 4 = 64. Apparently, you need imaginary numbers to solve it, even though the solution is real. Interesting.

  • @antonxuiz

    @antonxuiz

    6 жыл бұрын

    tifforo1 I was trying to approach to the solution with Bolzano's theorem and found it out too XD Also, what about using Ruffini 1 0 -15 -4 0 4 16 4 ---------------- 1 4 1 0 x^2+4x+1 x= (-4+-(16-4)^1/2)/2 = 2+-[2•(3)^1/2] = 2• [1+-(3)^1/2] There's the other two Maybe it's just that their formulas were useless xD

  • @stevesynan3910
    @stevesynan39107 жыл бұрын

    Awesome series! I had basically no intuition for imaginary (or lateral) numbers before watching this, and now I still have almost no intuition, but it's not nothing, which is something!

  • @jibcot8541
    @jibcot85413 жыл бұрын

    This is so good I am actually understanding this stuff! Great videos.

  • @rassilontdavros3004
    @rassilontdavros30046 жыл бұрын

    3:18 I’m confused, think I’m missing something... how does (15^2/27) equal 125?

  • @jacekborecki9171

    @jacekborecki9171

    4 жыл бұрын

    I was also confused, but there is small mistake. Should be 15^3/27.

  • @toastyarmor6858
    @toastyarmor68583 жыл бұрын

    3:19 the 2nd line is -(15^2)/27 the 3rd line should be -225/27 (or simplified), which is not -121 what gives

  • @rabeebibrat1805

    @rabeebibrat1805

    3 жыл бұрын

    That's a good point

  • @David-mm6nx

    @David-mm6nx

    3 жыл бұрын

    He wrote it wrong. It is supposed to be 15^3 as in the 1st line, c^3, which yields 15^3/27 AKA 125

  • @william97able2
    @william97able28 жыл бұрын

    I just discovered this channel and absolutely adore it!! Can you make another video about the history of golden ratio, fibonacci no. and pi??? My school's maths club would be delighted for the videos.

  • @juliepowers6037
    @juliepowers60374 жыл бұрын

    Great history lesson for myself and for my students! Thanks for sharing this!

  • @rifatkhan192
    @rifatkhan1925 жыл бұрын

    how can you let 3uv+c = 0??

  • @geminithetwins
    @geminithetwins4 жыл бұрын

    I wish I had a math teacher like this at school :(

  • @niteshsingh6375
    @niteshsingh63755 жыл бұрын

    I just watched this video and got amazed with the concept, everyone who has studied complex numbers has thought about its practical use but got no answers here I got something new.

  • @abc_cba
    @abc_cba6 жыл бұрын

    Nobody can explain any math concept like you. Salute !

  • @jacopoparenti9939
    @jacopoparenti99394 жыл бұрын

    Mario says: Zero is just a placeholder Luigi says: Numbers are lame, let's invade something

  • @htoodoh5770

    @htoodoh5770

    4 жыл бұрын

    Lol

  • @neverrip6809

    @neverrip6809

    4 жыл бұрын

    Zero is the capital letter in every equation ie, 0+6/2(0+3) = 0+1. What y'all are doing here is not maths... it's not an equation... it's a function... it's code... Binary code... FX function is not about working out the area of part of a circle. FX function is about drawing circles and curves using pixels! Remember FX Graphics in 1990?? In binary code, we don't use a capital 0 to start equations and we do not recognise brackets at all... 6/2(3) = 6/2*3 = 9. Maths is all but lost, binary code is the new religion. A religion where the devil has tricked u into believing there are infinite universes, black holes, wormholes, faster than light travel, an abundance of life in our galaxy, at the same time convincing u that he doesn't exist, and that even in infinite universes, there is not a god in any of them o.0

  • @arekolek
    @arekolek7 жыл бұрын

    In Italian "the letter pair gl, if followed by an i or an e, represents a sound similar to ll in million.", so basically, the g in Tartaglia is silent.

  • @ZombiesSlaier

    @ZombiesSlaier

    7 жыл бұрын

    arekolek nnnnnnnope.

  • @1violalass

    @1violalass

    5 жыл бұрын

    @@ZombiesSlaier He's right. It's pronounced Tartalya.

  • @ZombiesSlaier

    @ZombiesSlaier

    5 жыл бұрын

    @@1violalass helllll no, it's something like Tartaja, if you know a little bit of Spanish, Italian "GL" is like Spanish "LL"

  • @gruggi02

    @gruggi02

    5 жыл бұрын

    I am italian and nope, you're ABSOLUTELY wrong. Its sound is distinguished in "hard" or "sweet", depending on the vowel at the end. "Glabro" sounds "hard, "consiglio" sounds sweet. To hear how it sounds, please check any glottology vocabulary. In NO case, the sound of G is silent.

  • @vincentv.3992
    @vincentv.39927 жыл бұрын

    Your videos really are great! You explain it truly elementary and illustrative, so that one can really imagine what is going on I think. Thank you for that and keep it up please!:-)

  • @Expecto_proteinum
    @Expecto_proteinum3 жыл бұрын

    This is my first time on your channel. I subscribed right after I finished watching the first video because I saw the ad at the VERY END of the video! #Respect 🙏

  • @JohnGetchel
    @JohnGetchel8 жыл бұрын

    These are great! Love math history! If I may make a request. Can you leave the footnotes up longer? I was not able to read them. Or perhaps you could annotate them in the description.

  • @pulkitsingla7421
    @pulkitsingla74213 жыл бұрын

    Umm I've been taught that square root of 9 is just 3.. Calling it a negative 4 is actually a wrong concept.. negative square root of 9 gives us negative 3..

  • @insertname956

    @insertname956

    3 жыл бұрын

    sqrt(9) = 3 or (-3), is how I learned it though

  • @dominikscherer1882
    @dominikscherer18824 жыл бұрын

    This is one of the best explanations I heard about anything. Incredibly well done and "easy" to understand! I wish they could teach at university or school like this :/

  • @ssunvenomcast4975
    @ssunvenomcast49757 жыл бұрын

    Subbed going watch the rest of the series now!! :D

  • @hawthornroot
    @hawthornroot4 жыл бұрын

    i was watching US car crash vids & somehow i ended up here... now, for part 3, bye for now :)

  • @serdarcangul8391
    @serdarcangul83917 жыл бұрын

    3:22 2nd and 3th lines 15*15/27=125 wtf????? it equals something like 8,33

  • @michaelosborne7554

    @michaelosborne7554

    6 жыл бұрын

    It's supposed to be 15^3, not 15^2, and 15^3/27 does equal 125.

  • @hariramnarayanan5157
    @hariramnarayanan51574 жыл бұрын

    your videos are of top-notch quality and content !

  • @FREAKSLICER
    @FREAKSLICER2 жыл бұрын

    These videos have shown me how much fun a regular math class has sucked out of learning math. I’m actually interested in math for once in my life

  • @SoWe1
    @SoWe18 жыл бұрын

    I thought the root of a number, your example square root of 9, was defined as the _positive_ solution to the equation "x^2 = 9"? While -3 is also a solution of that it is not the square root of 9? That's how I learned it.

  • @r3g1t

    @r3g1t

    8 жыл бұрын

    +SoWeMeetAgain This is correct. A negative number can never be a square root by definition.

  • @PaveDearce

    @PaveDearce

    8 жыл бұрын

    +SoWeMeetAgain I also agree. -3 is not a square root of 9, though it is a solution to the equation x^2 = 9.

  • @TheRedclaw101

    @TheRedclaw101

    8 жыл бұрын

    +SoWeMeetAgain *"In mathematics, a square root of a number a is a number y such that y^2 = a, in other words, a number y whose square (the result of multiplying the number by itself, or y × y) is a.[1] For example, 4 and −4 are square roots of 16 because 4^2 = (−4)^2 = 16."* - Wikipedia I think you're talking about principal square roots.

  • @SoWe1

    @SoWe1

    8 жыл бұрын

    ฟ้าสรร ฮอว์ส yeah, that seems to be what the english wikipedia says. German wikipedia says it's defined as the positive number. See de.wikipedia.org/wiki/Wurzel_%28Mathematik%29 the formula in the subsection "Wurzel aus negativen Zahlen"

  • @hectorjoseberrios503

    @hectorjoseberrios503

    8 жыл бұрын

    From Algebra 1: For any real number n, the sqrt of n^2 = |n|. Proof available upon request.

  • @diabl2master
    @diabl2master7 жыл бұрын

    It's Fior not Foir -.- you even said it right but wrote it "Foir"

  • @JM-lh8rl

    @JM-lh8rl

    7 жыл бұрын

    Davy Ker It is right in the subtitles, though

  • @SkaterMisterAxe

    @SkaterMisterAxe

    7 жыл бұрын

    Davy Ker no it's foir

  • @vitakyo982

    @vitakyo982

    6 жыл бұрын

    Yes : Antonio Maria Del Fiore

  • @calculus3d130
    @calculus3d1307 жыл бұрын

    Good video. Minor critique: when you use the radical symbol for the square root of a number, it always stands for the positive root, never the negative.

  • @KTFG
    @KTFG4 жыл бұрын

    Excellent videos. Added to playlist.

  • @valentinachapovalova5470
    @valentinachapovalova54708 жыл бұрын

    The square root of 9 is not "also negative 3", the square root is positive by definition!

  • @ImmortalisPeregrinu

    @ImmortalisPeregrinu

    8 жыл бұрын

    Negative 3 *is* also a square root of 9. A square root isn't positive by definition; though the positive root is also known as the "Principal root," and that _is_ what he used the symbol for in this video. So he's still kinda wrong. But, we knew what he meant.

  • @AuroraNora3

    @AuroraNora3

    7 жыл бұрын

    +ImmortalisPeregrinu You're wrong. The *equation* has two solutions, but the *square root* of something is *always positive*. x^2=9 ** x=3 and x=(-3). But *sqrt(9)=3*. The square root is positive by definition. You should solve this equation knowing that *sqrt(x^2)=abs(x)*. x^2=9 sqrt(x^2)=sqrt(9) abs(x) =*3* x=3 and x=(-3)

  • @ImmortalisPeregrinu

    @ImmortalisPeregrinu

    7 жыл бұрын

    Hoo Dini The square root *IS NOT POSITIVE BY DEFINITION.* Please read: mathworld.wolfram.com/SquareRoot.html "Note that any positive real number has two square roots, one positive and one negative." Square root is a noun, Taking the principle square root is what you are referring to. Extra: *Solutions of a polynomial are also referred to as roots;* if there were only positive ones, unless all quadratics had multiplicities, only having roots greater than zero would break the Fundamental Theorem of Algebra for equations as simple as x^2-1=0.

  • @AuroraNora3

    @AuroraNora3

    7 жыл бұрын

    Also, try putting sqrt(x^2) in a graphing calculator, CAS, or Google. It will show you the result |x| and graph it for you.

  • @ImmortalisPeregrinu

    @ImmortalisPeregrinu

    7 жыл бұрын

    Hoo Dini I'm not insinuating that the range of the sqrt function includes negative numbers. It is considered a function because it it limited to show all square roots greater than zero. *BUT THE RANGE OF THIS SQUARE ROOT FUNCTION IS NOT THE FULL SET OF SQUARE ROOTS.* 'All' square roots will still include negatives. Again, please read what I linked you. It explains this. And for the love of god, stop wasting my time.

  • @inchicago
    @inchicago8 жыл бұрын

    You're wrong at 3:50, with the principal square root definition, every square root has only a positive answer. There are no negative answers to square roots.

  • @nicksm7980

    @nicksm7980

    8 жыл бұрын

    +David MacCumber, you don't really understand what square root is, do you?

  • @inchicago

    @inchicago

    8 жыл бұрын

    +Nick Sm Rarely do we consider the negative solution to square roots. Except for perhaps in the quadratic formula. Which is why when you type in sqrt(9) in any calculator you only get 3, not +/- 3.

  • @inchicago

    @inchicago

    8 жыл бұрын

    +Nick Sm Just scroll down and you will find others discussing this same idea. Although +/- 3 is a solution to x^2 = 9, it is not a solution to sqrt(9). For square roots, it's just the positive answer. Do YOU understand what a square root is??

  • @nicksm7980

    @nicksm7980

    8 жыл бұрын

    David MacCumber , √ sign is used for denoting only positive number. So, it's not really a square root sign, this is a so called principal (or arithmetic) square root sign. Square root is denoted by ±√. Thus, yes, his notation isn't accurate but his words are correct.

  • @inchicago

    @inchicago

    8 жыл бұрын

    +Nick Sm true

  • @draconiansolo
    @draconiansolo7 жыл бұрын

    Oh my god, this is as good as mr. Robot. Can't wait to binge watch it!

  • @ufotofu9
    @ufotofu97 жыл бұрын

    This series is incredibly well made and explained. Thanks.

  • @WelchLabsVideo

    @WelchLabsVideo

    7 жыл бұрын

    Thanks for watching!

  • @awseomgyhero
    @awseomgyhero7 жыл бұрын

    What about cube root of negatives??? get rekt maths

  • @Friek555

    @Friek555

    7 жыл бұрын

    the cube root of any negative real number is just another negative real number. 2³=8, and (-2)³=-8

  • @olayinkaanifowose5099

    @olayinkaanifowose5099

    7 жыл бұрын

    get rekt scrub.

  • @zairaner1489

    @zairaner1489

    7 жыл бұрын

    Like there are two square root for every nonzero real number, there are three cube roots for every nonzero real number. One of the is real and the otehr two are complex (the three cube roots form an equilateral triangle in the complex plane).

  • @ShankyBady

    @ShankyBady

    7 жыл бұрын

    Lmao you thought you're a mathematician, you're just a gamer

  • @viktor7536

    @viktor7536

    6 жыл бұрын

    This comment made my day

  • @steinal1169
    @steinal11697 жыл бұрын

    ...so imaginary numbers are real but I can't do a/0? ahuh, i'm onto you mathematicians.

  • @gamefoun

    @gamefoun

    7 жыл бұрын

    i think it should just equal 0, if you divide something into zero pieces you get nothing

  • @Crouchasauris

    @Crouchasauris

    7 жыл бұрын

    you're mixing it up. what you said would make sense if it was "0/a", not "a/0". (and 0/a does equal 0 like you believe it should)

  • @gamefoun

    @gamefoun

    7 жыл бұрын

    Grant Davis i know that 0/x = 0

  • @Crouchasauris

    @Crouchasauris

    7 жыл бұрын

    heheh, sorry. What I was saying was that a/0 wouldn't be like dividing something into zero pieces--it would be more like seeing how many 0's can fit into a. Even after infinitely many zeros added together, you still wind up with zero. Hence the "undefined" as opposed to something like "infinity"

  • @gamefoun

    @gamefoun

    7 жыл бұрын

    Grant Davis ok, thanks for explanation, I just thought it was dividing in pieces :D

  • @carletonification
    @carletonification8 жыл бұрын

    These videos are not getting nearly enough views. Great work!

  • @MadsWest
    @MadsWest7 жыл бұрын

    Love the visual means of educating about this, for me, hard topic. Definately better explained than by my math professor.

  • @obrod7080
    @obrod70804 жыл бұрын

    3:40 is factually wrong, square roots cannot be negative by definition.

  • @MatteoBrucato
    @MatteoBrucato7 жыл бұрын

    Is it really that hard to try to pronounce Italian names correctly?... -__-

  • @ripsumrall8018

    @ripsumrall8018

    6 жыл бұрын

    Is it hard for Italians to pronounce English names correctly? I'm guessing at times it is. Oh my bad, you said 'try to pronounce' not actually do it correctly. I'm sure they 'tried' and failed.

  • @Vitoria-ji6tq

    @Vitoria-ji6tq

    6 жыл бұрын

    yes

  • @plasticelephant1969
    @plasticelephant1969 Жыл бұрын

    Top tier videos on the topic, perfection.

  • @judgenap
    @judgenap7 жыл бұрын

    Fantastic Videos. I like the time line approach. It build a a better understanding . Thank you so much . This imaginary number have be bugging me for a long time . Didn't know the maths greats were in the same boat.

  • @bgnaruto11
    @bgnaruto118 жыл бұрын

    Awesome videos man! Thanks a lot!

  • @tdubmorris5757
    @tdubmorris57572 жыл бұрын

    This is pretty much the older shorter and better version of the veratassium video 6 years later

  • @cristiansamblas
    @cristiansamblas4 жыл бұрын

    Nicelyexplained. I really enjoyed it!

  • @Alan-jx1xp
    @Alan-jx1xp7 жыл бұрын

    I really like this series. It's really interesting!

  • @WelchLabsVideo

    @WelchLabsVideo

    7 жыл бұрын

    Thank you!

  • @JawadMohiuddin
    @JawadMohiuddin7 жыл бұрын

    This is awesome man! I regret coming here so late...

  • @bagrankus8589
    @bagrankus85893 жыл бұрын

    Çevirenlere çok teşekkürlerimi sunuyorummm Perfect video :)

  • @RamjetX
    @RamjetX7 жыл бұрын

    really enjoying this history and learning lesson. subscribed for more...

  • @nyanbrox5418
    @nyanbrox54185 жыл бұрын

    these videos are so freakin' awesome!!!

  • @matheuspeixoto2544
    @matheuspeixoto25444 жыл бұрын

    This is very good! Maths is curiously and very good, while very questions than or very true

  • @createtheengineerinyou6921
    @createtheengineerinyou69213 жыл бұрын

    I literally clicked the pdf for download accidentally but its a great treasure. Thank you for spreading math.

  • @rossboyd9801
    @rossboyd98018 жыл бұрын

    Good video, yet again! I like this series but please can we have a brief recap at the end of each episode?

  • @WelchLabsVideo

    @WelchLabsVideo

    8 жыл бұрын

    +Ross Boyd Great idea, I'll see if I can integrate these with future videos.

  • @ayoolajohn
    @ayoolajohn4 жыл бұрын

    This is so cool. Best math lesson ever!

  • @kmm2442
    @kmm24423 жыл бұрын

    You're very good. I love this.

  • @PinkeySuavo
    @PinkeySuavo Жыл бұрын

    I just wanted to remind what imaginary numbers were about, since I wanna to learn about quaternions, and I came across these videos. I remembered they were cool af and I wasn't wrong. Amazing series, thank you man. Actually if you did videos regarding quaternions in a similar way it would be so nice. For now I will stick to 3b1b videos.

  • @SteamPunkLV
    @SteamPunkLV6 жыл бұрын

    interesting and very nicely presented video. good job!

  • @kajalkhirodkar6521
    @kajalkhirodkar65213 жыл бұрын

    Amazing video.. loved it!!

  • @randyekrer431
    @randyekrer4313 жыл бұрын

    It really helps to think of negative numbers and imaginary numbers as not numbers, but operations/operators. They don't exist is real life; they help as intermediaries in problem solving.

  • @1959Berre

    @1959Berre

    10 ай бұрын

    That is true for all numbers, they do not exist in real life. Any number is but a representation of something. You can say: give me one apple, but you cannot say give me a one.

  • @pcky6646
    @pcky66465 жыл бұрын

    Thank's for the brazilian translate, subscribed! This is gold!

  • @peneeta
    @peneeta7 жыл бұрын

    These are so addicting! I love math now!

  • @ASMRChess
    @ASMRChess3 жыл бұрын

    this is gold

  • @joeg7849
    @joeg78496 жыл бұрын

    Well done explanation. Thanks

  • @mishumazumder1065
    @mishumazumder10656 жыл бұрын

    love this channel.

  • @coscomosco4388
    @coscomosco43884 жыл бұрын

    in del ferro's simpler version of cubic equation why did he use a negative d? any explanation?

  • @apucterio
    @apucterio7 жыл бұрын

    And you have subtitles! You won another subscriber