Linear combinations and span | Vectors and spaces | Linear Algebra | Khan Academy

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  • เผยแพร่เมื่อ 28 ส.ค. 2024

ความคิดเห็น • 251

  • @jennahaines9477
    @jennahaines9477 4 ปีที่แล้ว +255

    I have been watching Khan since I was in middle school for math help. Now, I'm at Georgia Tech and STILL getting A's and B's in math because of this man. All my gratitude. You deserve highest honors for teaching the world.

    • @dabidmydarling5398
      @dabidmydarling5398 2 ปีที่แล้ว

      What was your high school GPA? I'm a junior and I'm planning to apply for Georgia tech.

    • @jennahaines9477
      @jennahaines9477 2 ปีที่แล้ว

      @@dabidmydarling5398 Oh gosh I can't remember. I know I was just shy of getting Zell Miller. So... I think 3.69? Had high ACT scores though and dual enrolled. I think the extra stuff helped since my GPA was just okay in terms of Tech's standards. You can always transfer in- if you really want to go there, you can definitely find a way to do that! it's a great school and I highly recommend it!

    • @dabidmydarling5398
      @dabidmydarling5398 2 ปีที่แล้ว +1

      @@jennahaines9477 Hi! I'm also dual enrolled. We have a similar GPA and I am also planning to take the ACT (hopefully I do good on it 🤞🤞)
      Thank you so much for giving your experience. This really gives me perspective on how hard close/far I am.
      Did you do any tech-related extracurriculars? Which extracurriculars should I be doing?

    • @muhammadashshiddieqi8653
      @muhammadashshiddieqi8653 ปีที่แล้ว +1

      ĹBBBŞČ MÅÝ F W Ù ÑĒĒĐ ĒŞP ČÒÙŘŞĒŞ Ñ ĶÀHVÈÌÑ ČÒFƏĔŞHÒP Ñ MZ.ŞHÌDĐÌĒQÌ ÇHÈÇĶÌŤĹBBBŞČ MÅÝ F W Ù ÑĒĒĐ ĒŞP ČÒÙŘŞĒŞ Ñ ĶÀHVÈÌÑ ČÒFƏĔŞHÒP Ñ MZ.ŞHÌDĐÌĒQÌ ÇHÈÇĶÌŤ

    • @sanguinelinguine
      @sanguinelinguine ปีที่แล้ว

      Georgia Tech can be really iffy. It’s probably more based on extracurricular activities. I had 4.0, 33 ACT and got in, while my friend had 4.0, 35 ACT and didn’t. I’d say if you have solid academics, really work on leadership and community service roles.

  • @kyledomen2627
    @kyledomen2627 3 ปีที่แล้ว +103

    This quote really helped me understand the concept.
    "If vector a and vector b spans R2, that tells us any vector in R2 can be represented by a linear combination of vector a and vector b"

  • @adrianchivas2014
    @adrianchivas2014 9 ปีที่แล้ว +159

    Thank you khan for helping me understand this. I am taking Linear Algebra my sophomore year in college. Anyways, all I have to say is that you are the real MVP!!!
    Always, remember that you are changing lives and I am in college because of you my friend. On track to become an Electrical Engineer.
    On behalf of everyone that admires you, Thank you!!!

    • @benpotter3278
      @benpotter3278 7 ปีที่แล้ว

      adrianchivas2014 I am In 7th grade and I'm learning this

    • @jacobm7026
      @jacobm7026 5 ปีที่แล้ว +18

      by the way, i'm in kindergarten and am loving vector spaces and the alphabet

    • @Dan-gc3ke
      @Dan-gc3ke 5 ปีที่แล้ว +7

      smh I'm in pre-school and I'm learning this

    • @ProLeopardx1
      @ProLeopardx1 5 ปีที่แล้ว +2

      @@katb9776 Nah, I don't know what school you went to but I wasn't taught vectors until calculus. I'm learning linear algebra right now after Calc 1, 2, and 3 (multivar). It's combined with multivar calc at my college and I hate it. Everyone's doing far worse in this than they did in calc 3.

    • @SanaZub
      @SanaZub 5 ปีที่แล้ว +4

      im in daycare and im learning this!!! just turned 3 yesterday! woot woot MATRICES R LITTTTTTTT

  • @economicswithozzy
    @economicswithozzy 5 หลายเดือนก่อน +15

    2024 maths is still same 😂😂😂

    • @Got-it747
      @Got-it747 2 หลายเดือนก่อน +3

      Because reality is still the same

  • @mrjoni54
    @mrjoni54 10 ปีที่แล้ว +90

    3:47-3:52 " Hey Sal, why are you even introducing this idea of an linear combination?"
    "Beacause I wanna!"

  • @nlnrose
    @nlnrose 8 ปีที่แล้ว +42

    ... you explain this better than my college matrix algebra teacher... wow I actually am starting to understand this.

  • @jappmayo1220
    @jappmayo1220 9 ปีที่แล้ว +218

    I just paused this halfway to say THANK YOU for helping me to understand this!

    • @Station1643
      @Station1643 4 ปีที่แล้ว

      but u asian, why u no understande ?

    • @uddipanbaruah6021
      @uddipanbaruah6021 4 ปีที่แล้ว

      @@Station1643 abbeeyyy kije hbo mane

    • @Station1643
      @Station1643 4 ปีที่แล้ว

      @@uddipanbaruah6021 abbe me no understand Indian

    • @uddipanbaruah6021
      @uddipanbaruah6021 4 ปีที่แล้ว

      @@Station1643 its ok.. Jai Ai Axom

    • @mahadevhatti5228
      @mahadevhatti5228 4 ปีที่แล้ว

      @@Station1643 doe youe understande whate youe saide ??

  • @WalidFeghali
    @WalidFeghali 13 ปีที่แล้ว +72

    I passed Linear Algebra because of these videos. You're the best, Khan!

    • @pinklady7184
      @pinklady7184 3 ปีที่แล้ว +1

      Nah no noo, he da best and *BESTEST!*

  • @vanessang4216
    @vanessang4216 8 ปีที่แล้ว +32

    You are a true blessing to the world

  • @alechenderson8410
    @alechenderson8410 11 หลายเดือนก่อน +5

    shoutout to anyone else with a bad linear algebra prof

  • @bobbypesch5220
    @bobbypesch5220 4 ปีที่แล้ว +4

    vibing in my dorm rn but had to give a shoutout to Sal, this man got me into college

  • @EwoudCP
    @EwoudCP 14 ปีที่แล้ว +7

    Wow. This is really useful. I've been trying to make sense of the idea of the span, but I tend to see things other people don't. More frustratingly, I tend to not see things that other people do. Thanks for the video. I'll definitely keep your playlists in my bookmarks.

  • @TheBlackZoe
    @TheBlackZoe 7 ปีที่แล้ว +6

    Using this "pseudo-proof" system: drawing the vectors as a visual method is such a great representation of the idea of vector space. Thank you. Greetings from Greece.

  • @eleazararce5716
    @eleazararce5716 ปีที่แล้ว +2

    About to take this class for a second times after 13 years of being out of school. Its should be fun and interesting this time around!! I will be utilizing these videos too!!

  • @mabeklvista
    @mabeklvista 11 ปีที่แล้ว +3

    why is this 10 times better explained than in lectures? they go so fast, here i can learn on my own speed. Thank you Sal!

  • @Zurh1994
    @Zurh1994 12 ปีที่แล้ว +5

    They've explained me this for 3 consecutive years. Every year I fear this explanation because I can't picture it, I don't know why is it useful, and now it's really like I can see the truth hahaha.
    How can you explain everything so nicely in every single video and my teachers be so useless? XD

  • @krose7406
    @krose7406 11 ปีที่แล้ว +12

    i gave up and just started watching the lectures DURING class!!

  • @selingermann5599
    @selingermann5599 5 ปีที่แล้ว +6

    I have finally reached ENLIGHTENMENT!
    Thank you.

  • @danielcohen9637
    @danielcohen9637 4 ปีที่แล้ว +2

    How do you know so much? You know math, accounting,business, computers,physics and more.

  • @VSpooner
    @VSpooner ปีที่แล้ว

    this makes understanding the math so much better, rather than just showing the process you manage to show the process of understanding.

  • @rowanfrankenbach3625
    @rowanfrankenbach3625 2 หลายเดือนก่อน +1

    7:57 the "SPAN" he said it with gusto lmao. sal is legendary

  • @roxymang1
    @roxymang1 10 ปีที่แล้ว +6

    so helpful! i was stuck on a question all day reading the textbook, then i watched this video and now it's clear :D

    • @danteeep
      @danteeep 7 ปีที่แล้ว

      exactly what happened to me

  • @Batooya
    @Batooya 10 หลายเดือนก่อน

    idk if you (the person teaching in the vid) will ever read this but I, and I'm sure others as well, have come to find you and your lessons to be really comforting

  • @nathandrouillard2927
    @nathandrouillard2927 7 ปีที่แล้ว

    Thank you. These concepts aren't even that hard, but my prof speaks in VERY broken English and teaches very poorly on top of that so I absorb close to nothing in my lectures. These videos are a godsend

  • @drahoo302
    @drahoo302 8 ปีที่แล้ว +6

    15:46 You Sir, just wrote it perfectly :-)

  • @fadlmasri
    @fadlmasri 3 ปีที่แล้ว +1

    the fact that this vid is 11 years old and it still helped me is outrageous

  • @theotydingco7987
    @theotydingco7987 9 ปีที่แล้ว +18

    18:00
    How do you get from 3c2 = x2 - 2x1
    to c2 = 1/3(x2 - x1)
    Where does the "2" in -2x1 go?

    • @mandy1339
      @mandy1339 8 ปีที่แล้ว

      +Theo Tydingco did you watch the video all the way to the end? you can see what happens

    • @theotydingco7987
      @theotydingco7987 8 ปีที่แล้ว +2

      +mandy1339 yeah figured it out.

    • @patmull1
      @patmull1 8 ปีที่แล้ว +1

      +Theo Tydingco Yeah.... I was like "PHEW... thanks god" :D

    • @sahil5185
      @sahil5185 6 ปีที่แล้ว +1

      Yeah I was so stressed out until he corrected it lol!

  • @sherajr
    @sherajr 14 ปีที่แล้ว +2

    I'm so glad I found this before my midterm!!

  • @Fallen_Fly
    @Fallen_Fly 12 ปีที่แล้ว +1

    Thank you, linear algebra and differential equations has changed my opinion about math from completely in love to loathing it. Hopefully with your videos I can get my passion back.

  • @SporkyG
    @SporkyG 11 ปีที่แล้ว +7

    he corrects it at 19:26 :)

  • @waseem1173
    @waseem1173 13 ปีที่แล้ว

    Now thats a real teacher. man i love you . you're a life saver

  • @witnessforchrist7778
    @witnessforchrist7778 6 ปีที่แล้ว +1

    Not even 3 minutes into it, I've learned more from Khan Academy so far than 8 weeks of linear algebra in class. My teacher sucks at explaining, he's all over the place, he has a strong accent, his hand writing sucks, nor does he explain terminology.

  • @necatiakpnar5677
    @necatiakpnar5677 6 ปีที่แล้ว

    your video uploaded in 2009 but still helping to people understand algebra. Thanks for everything!

  • @omardanial7351
    @omardanial7351 5 ปีที่แล้ว +7

    Thanks Sir Salman Khan..
    You saved my semester of engineering.

  • @fluffio2976
    @fluffio2976 7 ปีที่แล้ว +5

    *Comes back an hour after having paused the video* "The actual fuck has he drawn."

  • @SochoChun
    @SochoChun 13 ปีที่แล้ว +1

    sweet... it's much better than my professor's lessons, this is a really good revision lesson before my test

  • @slykni8
    @slykni8 27 วันที่ผ่านมา

    Wow, you are a real genius.
    You just cleared my doubt.❤❤❤

  • @desxse6309
    @desxse6309 5 ปีที่แล้ว +1

    Thank you so much. After I watch this, I understand linear independent, linear dependent and why free variable relate to them.

  • @bgraaman89
    @bgraaman89 2 ปีที่แล้ว

    I might receive flak for saying this, but this Linear combination video of yours is much better than Dr. Gilbert Strang's MIT video. You've explained it much better than he did. Thank you.

  • @McDreamOn
    @McDreamOn 12 ปีที่แล้ว

    Have an exam tomorrow over this stuff and I just had an ah ha! moment!!!!! So much clearer than my professor!

  • @Sekkonal
    @Sekkonal 12 ปีที่แล้ว +1

    At 17:59 he multiplies both sides by 1/3 to remove the coefficient from 3C sub-2, and on the right side of the equation he drops X sub-1's coefficient? Is that an error or am I just not seeing where that coefficient went?

    • @Darlenei
      @Darlenei 8 หลายเดือนก่อน

      I wondered the same? @Khan Academy ?

  • @zhongqiren6794
    @zhongqiren6794 8 ปีที่แล้ว +1

    God bless you, Khan, Thank you very very very very much.

  • @haro123ish
    @haro123ish 13 ปีที่แล้ว

    love you man, i always wondering what a span was. my teachers have failed to explain this so far. thank you

  • @evelynecheung1905
    @evelynecheung1905 3 ปีที่แล้ว +2

    2020 and this is still saving lives thank you so much !!

  • @lilonepj
    @lilonepj 4 ปีที่แล้ว

    Thanks for the videos. Please add practice problems for the linear algebra topics!! I can only find 4 practice sets for the vectors section.

  • @yusuf1597
    @yusuf1597 8 ปีที่แล้ว +26

    At 6:18 Sal turns into a Canadian.

    • @dybiosol
      @dybiosol 8 ปีที่แล้ว

      I see what you did there!

    • @ataadi1460
      @ataadi1460 6 ปีที่แล้ว

      Everyone saw what he did there.Any issues?

  • @danielgonzalezisaiev9643
    @danielgonzalezisaiev9643 11 ปีที่แล้ว

    Love your videos! The thing that makes great lecture videos is the person talking and their pedagogic skills and you sir, YOU GOT EM'! Great presentation, great understandable language, thanks so much for your videos!

  • @publicanimal
    @publicanimal 13 ปีที่แล้ว

    You are a god. with the graphical representation of vector space R2 I finally understood the concept of linear combos. thanks

  • @amayashenuri1147
    @amayashenuri1147 6 หลายเดือนก่อน

    just an amazing teacher❣

  • @kjz8923
    @kjz8923 5 ปีที่แล้ว

    thank you Khan ! i’m taking linear algebra in my junior year in high school! This video helped a lot!

  • @Edwrath
    @Edwrath 13 ปีที่แล้ว +7

    My University Day:
    -Sleep through morning lectures.
    -Watch khanacademy versions of my lectures
    -Play guitar all afternoon

  • @tsaras2838
    @tsaras2838 3 ปีที่แล้ว

    your voice gives me hope.

  • @razberrycreme
    @razberrycreme 12 ปีที่แล้ว +1

    You are an amazing teacher. Thank you!

  • @imegatrone
    @imegatrone 12 ปีที่แล้ว

    I Really Like The Video Understanding linear combinations and spans of vectors From Your

  • @MrAntihumanism
    @MrAntihumanism 11 ปีที่แล้ว +1

    love this!!

  • @Ben1220
    @Ben1220 14 ปีที่แล้ว

    You're absolutely right, it doesn't matter how many vectors you have, linear combinations are defined for any set of vectors. He probably should have chosen a different name for the first n, but this doesn't matter if you realise that the two n's are different.
    Well done for spotting that :P

  • @sophmcamp
    @sophmcamp 5 ปีที่แล้ว

    binging many of these videos before my final because I rarely understood my professor’s explanations

  • @Menor55672
    @Menor55672 3 ปีที่แล้ว

    Thank you Mr. Khan

  • @fliskmayhem
    @fliskmayhem 12 ปีที่แล้ว

    @LostAngel01234 First of all, you'll need at least 3 diffrent vectors (call them v_1, v_2 and v_3). Each with dimension 3, so they'll look like (x,y,z). Second, it must be impossible to write one of these vectors as a linear combination of the other 2 vectors. I.e. : c_1 v_1 + c_2 v_2 + c_3 v_3 = (0,0,0) only if c_1 = c_2 = c_3 = 0, the three vectors span R3. If there's another solution for the c_i's, it means the vectors span up a plane or a straight line in R3, but not whole R3.

  • @ExecutiveGoth
    @ExecutiveGoth 3 ปีที่แล้ว

    This saved me for my high school exams thanks so much

  • @bryannamelenhorst
    @bryannamelenhorst 14 ปีที่แล้ว

    thank the lord i found these video's. you are an amazing teacher!

  • @shibsankar4569
    @shibsankar4569 5 ปีที่แล้ว

    Best and simple to understand

  • @oluwatoba11
    @oluwatoba11 13 ปีที่แล้ว

    I think I need to take some moment of pause sometimes in the exams too! Great guy!!!

  • @wjestick
    @wjestick 11 ปีที่แล้ว

    Magic formula. Watch this video before you cover LA in the lectures. Then use the lectures as revision! It is a lot easier to pay attention when you are actively listening.
    And with two reviews you are much more likely to retain the material.

  • @ieatnoodls
    @ieatnoodls 2 ปีที่แล้ว

    I'm out of words how I can finally understand this

  • @SoloPro
    @SoloPro 8 ปีที่แล้ว

    your videos are actually enjoyable to watch... hope the best for you for being this kind to share your knowledge with us all :D Keep it up! PEACE

  • @chiupaulpaul
    @chiupaulpaul 7 ปีที่แล้ว

    I'm so glad you made this video.

  • @dansam5467
    @dansam5467 5 ปีที่แล้ว

    Thanks for the help

  • @PrabhuShreeRamKiJai
    @PrabhuShreeRamKiJai 9 ปีที่แล้ว +2

    hey Sal,
    Can you please tell me why 3A+(-2B) vector is parallel to Y axis like this you had shown ....?/

  • @GiggleJuiceee
    @GiggleJuiceee 5 ปีที่แล้ว +6

    I was 7 in 2009

  • @fauziahassan9938
    @fauziahassan9938 3 ปีที่แล้ว

    Hey sir thank u sooo much for this video .....

  • @adam.phelps
    @adam.phelps 14 ปีที่แล้ว

    @Ace12174 He multiplied by -2 so he could find one variable at a time - which in this case wasC2 - so after he found the value of C2 he could find the value of C1. Its called solving a system of linear equations by using elimination.

  • @satyajeetbunty6550
    @satyajeetbunty6550 3 ปีที่แล้ว

    Thank you 🙏

  • @hai2410
    @hai2410 14 ปีที่แล้ว

    @Ben1220 and @thomapple
    I think he's right actually. R^n is n-tuples of real numbers. If you're working in R^2, you have two dimensions to work in and so you get [x1,x2], R^3 [x1,x2,x3], so it follows from that.

  • @tomasdzvonik4998
    @tomasdzvonik4998 ปีที่แล้ว

    Thank you

  • @carolllj
    @carolllj 4 ปีที่แล้ว

    thank u so much my lifesaver

  • @damnfreakingsien
    @damnfreakingsien 5 ปีที่แล้ว

    THANK YOU!!! i was finally able to visualise this frustrating concept.
    Time to rush my homework before deadline...... :(

  • @edgbaston149
    @edgbaston149 3 ปีที่แล้ว

    Thank you so much Sir🙏

  • @river.
    @river. 3 ปีที่แล้ว

    13:11 finally understood span

  • @shrutikasansaria8499
    @shrutikasansaria8499 4 ปีที่แล้ว

    The explanation is just awesome 🤩

  • @khashya786786
    @khashya786786 12 ปีที่แล้ว

    This is real charity work!

  • @krishonweb
    @krishonweb 4 ปีที่แล้ว

    I love you man! What an explanation

  • @towbsmedia
    @towbsmedia 3 ปีที่แล้ว

    Cheers brother; great job. thank you

  • @Nandeesh_N
    @Nandeesh_N 3 ปีที่แล้ว

    @Khan Academy Should the scalar value which is used to multiply the vector belongs to a real value? if yes, at the end, the c2 obtained is a fraction.

  • @anandib5401
    @anandib5401 3 ปีที่แล้ว +28

    2 minutes silence for those who are watching this in 2021.

    • @anandib5401
      @anandib5401 3 ปีที่แล้ว +1

      By the way, I was just 1 y/o in 2009

    • @brightknight0623
      @brightknight0623 11 หลายเดือนก่อน

      @@anandib5401who

  • @talha6k
    @talha6k 14 ปีที่แล้ว

    You are great! God bless....

  • @shashankverma8939
    @shashankverma8939 4 ปีที่แล้ว

    thank you sir

  • @ceciliaosorio7746
    @ceciliaosorio7746 6 ปีที่แล้ว

    Thank you so much for this very helpful video!

  • @Ace12174
    @Ace12174 14 ปีที่แล้ว

    This is definitely helping me understand span. It's starting to sink in! lol Thanks! There's one question I have though, why do you multiply (at 17:24) when finding any C1 and C2 by -2? thanks =) (Grade 12 Calculus and Vectors)

  • @jhl849
    @jhl849 6 ปีที่แล้ว

    Thank you for very good explanation.

  • @MisterTutor2010
    @MisterTutor2010 11 ปีที่แล้ว +11

    "All linear combinations are linear combination"
    Furthermore all Tautologies are Tautological :)

  • @alikoteich6639
    @alikoteich6639 5 ปีที่แล้ว

    Your crosshair is amazing for csgo

  • @zack_120
    @zack_120 3 ปีที่แล้ว

    4:50 - the graphic coordinates in increments of 2, not 1, is counterintuitive, reducing lecture efficiency.

  • @danteeep
    @danteeep 7 ปีที่แล้ว

    I can't thank you enough for this video

  • @thomapple
    @thomapple 14 ปีที่แล้ว

    Hey, I've got a question for you: at the very beginning, you write:
    v1, v2, ..., vn in R^n
    But does that mean you have to choose the same numbers of vectors as the number of dimensions you're working in (n in this case)? (uh sorry for my English, I hope this is clear)
    Wouldn't it be better to write for instance:
    v1, v2, ... , vi in R^n ?

  • @elinorwang2705
    @elinorwang2705 9 ปีที่แล้ว

    It was so helpful:) Thanks a lot!

  • @Robertlavigne1
    @Robertlavigne1 11 ปีที่แล้ว

    I cant tell you how much I love this man!! I want to kiss him on the mouth!!! 4 days till my LA final and I was getting so frustrated. Now its all clear!! Thank you so much!!!

  • @Zurh1994
    @Zurh1994 12 ปีที่แล้ว

    Nobel prize for this guy, please!

  • @JesusAxolotl
    @JesusAxolotl 13 ปีที่แล้ว

    @Feroyn totally agree!

  • @roberthoffmann930
    @roberthoffmann930 3 ปีที่แล้ว

    omg thanks