Complex Numbers (part 1)

[ullasrajchellappan1]

I dont understand why the college teachers cannot teach like this...they take way too much time, but only end up confusing the students. May be because they get paid too much...!!

[danusv]

6 professors are worried about losing their jobs...

[Chowmeingeejah]

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

[kluvfashion20]

@Chowmeingeejah standard form =)

[Chowmeingeejah]

@kluvfashion20 ah.. gdgdgd

[mrshackztor]

Sal is great, but some of this shit I still don't understand at all when he explains it.

[mrshackztor]

Seriously, who the fuck had the idea to use letters in math?? AND FOR THE LOVE OF GOD, WHY?!!

[mrshackztor]

Yeah.....um.....

what?

[GnosticHumanist]

Man I want Khan's cock in my arse so bad right now!

[brenoakiy]

@GnosticHumanist lolwut?

[antoinetteluvk]

Okay, so I have a really bad math teacher. He doesnt explian to use the principles whatsoever. He just gives us a problem to solve then he solves it, then he expects us to do the rest on our own. Now, I knew about Khan Academy so I watch the videos all the time. This is how I learn my math.. If i was brave enough to tell my math teacher to just let us watch a video from Khan Academy, I'd do it.

[MilitaryMan006]

what is the square root of i?

[frxstrem]

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

[eazybreezyxoxo]

omg this stuff is so hard i want to cry !!

[thepope229]

i looked this up cause im bored

[t6089745]

@thepope229 u definetly are from a different planet

[adillsonn5555]

what program is it that let you write in the black board?

[aDyslexican]

@adillsonn5555 i believe he uses microsoft paint

[mohbehnia]

@aDyslexican me too :)

[JayantKumarZ]

nice! so they behave as vectors huh? sweet! :3

[thelastvampirehunter]

This video helped out a lot, thank you!

[YoungKnoccOut]

Thanks alot i failed my test because i watched this

video halfway and it was at the last minute! give me ur adresss cuz im coming over and kicking sum ASS !

grabs chuck norris

[waleedsrahmatullah]

Not to be critical (this helped a lot BTW)...but this is perhaps your worst video! If you could re-do this in HD and fix your 'i's and that mistake etc. this could be 100x better!

[JayantKumarZ]

@waleedsrahmatullah not even 1.01x better. Its the best at its best.

[issunRyuBlackBelt]

Found this right after my test. Of course.

[bysabrinart]

Some question use i as j... Quite confusing and make me nervous when i receive the exam paper

[TOLIDEP001]

6 people can't imagine imaginary numbers.

[hyper4391]

thanks dude.

[latinschoolofchicago]

Astounding! He sounds exactly like Joe Morton! (the narrator of "Invisible Man").

[frostshadow5]

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

[duliptulip]

@frostshadow5 He factorised out +i, thus leaving (b - d)

[Ecdub984]

@frostshadow5 he just seperated the real numbers from the imaginary numbers

[MrMunkiiz]

Not bad,Not bad

[kkssw]

Thanks!

[LFCPlatina]

thanks! i'm going to take the GCSE on november so this video really helped me!

complex number is really complex and going numb lol

[fin5ley]

Why was this video in the related video list while I was watching something about Zalgo?

[flyguy1012234]

i would they even teach us this dumb shit. it makes NO SENSE!!!!! now i have to study something i dont understand because i have a test on this the FIRST FRIDAY OF THE FIRST WEEK OF SKOOL!!!!!!!!!!!!

[xMusicxxlovex]

The only reason there are dislikes are because people probably just don't like complex numbers lol

[88joeana]

helped me soo ssooo soo soo soo sooo sooo soo soo soo soo soo soo sooos ooo sooo much<3

thanks xD

[Kabitu1]

thank you...

[hiimcb]

it's people like you how make the internet a better place

[wear2whale]

why don't more teachers teach like this?

[st0nedoldman]

Can someone please tell me where I went wrong here?

If i^2 = sqrt(-1)*sqrt(-1),

then i^2 = sqrt(-1*-1),

which =sqrt(1)

which is 1.

I know I must have gone wrong somewhere but I cannot see where.

Someone told me that surds do not apply to complex numbers but that is clearly wrong, eg.

sqrt(-5)=sqrt(5*-1)=sqrt(5)i

[DJYPP3]

@st0nedoldman

sqrt(-1)*sqrt(-1) = (-1) = i^2

Since square root of a number multiplied by the square root of the same number will always equal the number.

Example sqrt 9*sqrt 9 = 3*3 = 9

Square root 9 is equal to three, therefore square root 9 multiplied by square root 9 is equal to 3 multiplied by 3

which is 9.

Hopefully this helped, it would be a lot easier to show you on a piece of paper

[conducttracks]

Goober gaba geeba gooba (ZZZzzzz), Brain malfunction!, Rebooting now!

[jerome1470]

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

[wisherwatch]

it's crazy...i mean why imaginary when it's only (-1)

[imranbug81]

yeah right now we are imagining numbers.. huh imaginary numbers... :-/

[apoorvaroy]

thnxxx



[Calz4]

lol i was thinking "10seconds left, how is he gonna finish it all ;) good videos btw,

i love them all

[sauri2005]

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

[alZiiHardstylez]

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

Fate?

[0riginalrick]

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.

[zoom2121]

"I'm using the word imagine too much" lool

[toolbass24]

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

[alanimoikan]

i wish you was my teacher in maths :/

[shiza223]

you are a hero!!!

[avinaashnash100]

damn easy

[Wafffl3]

My i's aren't looking good :P

[TheKinza99]

i understand ........yummy

[sssandeep619]

it is nice

[25911454]

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

[IAMMATSUDA]

@25911454 maybe in math, but not in any other class with spelling like GUD :)

[Chowmeingeejah]

@IAMMATSUDA have you never heard of short hand informal writing

[SimpleC0mplex]

test tomorrow you are a saint good sir

[Agentkross]

Thanks for the video. I could not understand my TA's rushed lesson on this.

[francecharly]

verrrrrry gooooog the best

[cchhrriiss825]

this used to be so easy

[Darktmt]

thanks

[caseywtw]

At 0:40, i squared IS NOT -1, it is 1.

[Arkanovi1989]

@caseywtw Actually no, Sal is correct, it's -1

[mmSeven77]

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

[SexyNeverLeft69]

it seems like this guy knows everything

i downloaded his clips about biology on to my iphone he's pretty awesome!

[12cyberspy12]

if your name is aakriti then i love you....

[Bugsykato]

im in 10th grade, is this too advanced for me...

[samuel1abarza]

Oh sal when you die (which i really really hope it doesn't happen soon) please possess our teachers!!! You are simply the best!

[mileymileyismylife]

"clear bitch" AHAh (like 4:20ish

[Gearhe1d]

@mileymileyismylife I think he said "clear image".

[abdalgoboria]

howd can use the mouse and ur computer as a board or a paper ?? is that Paint or a special program can u please tell me thx

[mitch9144]

hey guys!! you can use this site, so it will help you understand the complex number.

[somewog]

im so high

[ABCba5tard]

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

[martmelee]

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

[hifhif123]

isn't the square root of -9 both + or - 3i

[glasman857]

UM-TUT-SUT/SURE WHY NOT

[70925007]

i dnt get how he runs out of time?

[cantryss]

@ 4:13 Sal almost bursts out laughing at bi

[70925007]

no he doesnt.

[k0du123]

how does this have any applications in real life?

[JoeClawsy]

@k0du123

It's used in electronics and fluid mechanics

[Nick964]

everyone in class asks that but thats not really the point.

school is basically testing you for comprehension on certain materials. this probably has no application in real life, but its just difficult material that they can see if we are good at or not.

[Dice3000]

shitty graphics :D

[Bagsterflop]

Very interesting, I hope I do this at school some time, I'd like to study this further.

[braydenbeautiful]

simple concepts

I did this in 6th grade.

Still, very well done for anyone trying to learn the concepts.

[70925007]

wow ur so smart! how can i be like you??

[braydenbeautiful]

@70925007

Your sarcasm aside, it has nothing to do with inelegance.

My country's school system is simply fast-paced.

[70925007]

Fast-paced my ass, u can't even spell Intelligence! (Inelegance means gracelessness, or clumsiness)

[Solcito1235]

lol, understanding this makes me feel smart xD

[muranvya]

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

[IMBLUESTREAK23]

Nothing exists, the world is going to explode because of the letter i

[natetitus52]

You're a great math teacher!

[patilnikh]

I hate Maths because it's so easy, just the "terms", "symbols" makes it look COMPLICATED.

[jumpman1824]

uhm yeah, after using the letters such as (a+bi) etc. you should use examples. with numbers you know it would be a little bit more helpful.

[xonkarate]

I do agree!

working with the lettres is easy

but having numbers such

(4-2i) - (3+5i) one has to open brackets first, and then continue on the method which s being used in the video!

(4-2i) - (3+5i)

(4-3) = (-2i-5i) = 1-7i

anyway, after all, helpful tutorial! thanks!

[philjc54]

Sal, just a thought, with reference to the complex number a + bi, is it not the case that just b is the imaginary part? Certainly bi is an imaginary number, but I was taught that b alone (i.e. without i tagged on) is termed the imaginary part.

[casplash4]

your alsum!

[orelhai]

u rock

[demisous]

your the best :)

[wIzZaRd4893]

TeamFortressNoobspy im actually surprised that you would watch this video, being only 14. I would have blown it off as useless when i was that age (lol im 16). But if you have advanced maths at your school in senior then i highly recommend that you do it because you may never ever use it (although chances are if you do some sort of engineering or something very maths involved then you will use it) its damn interesting. Great video. I'm doing this is in maths and this has reinforced it for me.

[ultimage7]

Lol..

I just turned 14 a little over a month ago and I'm using this in Pre-Calc (Junior year).

[nugg69]

let me switch colours its getting monotonous. LOL

[TeamFortressNoobspy]

i might be cnsidered ignornt hre being 14 but whn th hell m i going to use this in my life, plz dont give me hard time about it though

[neakhu]

It's useful for engineering.

[mzc29]

its used a lot in electrical engineering when dealing with capacitors and inductors.

[fassterblade]

@mzc29 also quantum mechanics

[thelastwords]

1. Learn to spell.

2. It is used in many areas such as engineering and other physics related fields.

3. Even if you wouldn't use it in your life, you should still appreciate the beauty of mathematics and the fact that such things can exist.

[xhochdrei]

that´s so easy :D

[famecieux]

thank you so much now,, im gonna make math easy ..

[NateMan58]

Sweet thanks mate!

[gimmeurdosh]

The (b+d)i was oddly layed out. Its basically factorisation, which i would always lay out as i(b+d)

[qn5r]

That kind of defies the point in the video.

[gimmeurdosh]

not really. Its the same thing, just layed out differently.

[qn5r]

In a way, but in order to show it is the imaginary part it is put after. Otherwise it could just be a variable called I.

i is a constant not a variable. It is the definition of the root of -1. As he says in the video.

[gimmeurdosh]

so basically you're saying that you lay it out differently so you can differentiate in your mind between complex and real numbers?

[qn5r]

Yes, otherwise I could simply be seen as a variable.

[d0thma]

very helpful. for some reason my college courses I am expected to just know this stuff, with nothing more than a small blip in the preface of the text book about imaginary numbers.

So i must have missed this class in high school, thank you so much for making this video.

[qn5r]

It's no that difficult at the beginning but later it gets more involved!

[heatboy99]

Why do you use letters instead of numbers? I mean the a b d, i think it makes stuff more confusing.

[qn5r]

Its representation of variables. A number is a value. If a number was used then format and formulas couldn't be used.

[222804425]

nice but a bit confusing

[danieltian]

hey isnt it easier if u use a smart board its what my teacher uses

[JAM1SN]

no, cause then he would need a camera, and a room to shoot in, and would have focus issues and such, this is really good cause he can do it ne where, all he needs is a PC with Paint, his Tablet, a mic and a screen capture program.

[Lolzerd]

yah, he uses paint, and i think he records with hypercam2 maybe

[apparent123]

what software is it? pliz?

[JAM1SN]

its paint, with a drawing tablet

[BlueMicrowave]

my teacher uses microsoft's 'onenote' to do presentations. it makes it easier and it's more organized, you should check it out. plus, erasing is a breeze.

[blackdranfire]

Can angles have imaginary mesures?

[darijo203]

You can say that some real number N is in fact a special case of complex number N+0i

[theperfectdrug01]

very helpful video!

[yakmuck]

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

[kieranfung96]

yes its for high levels

[lge123]

can u use numbers ?

[fernsbro]

at 7:58, if i=-1, wouldn't i x i =+1?

[welsh4life96]

your voice suits math.

ordered but fun

[Perrickan]

Ha!

[Harry0Ron0Hermione]

Is this for high lvls?

[mgallegos55]

thank you sir

[Nandine2]

oh my god i love you!

[Max11551]

Cool! Thanks. :)