How to expand (a+b)^n (Binomial Theorem with a combinatoric approach)

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  • Опубликовано: 25 ноя 2024

Комментарии • 281

  • @lonelybookworm
    @lonelybookworm 5 лет назад +992

    (a+b)² = a²+b²
    That's enough RUclips for today.

  • @gnikola2013
    @gnikola2013 5 лет назад +262

    0:02 Newton was literally trembling and shaking

  • @TheDslide
    @TheDslide 5 лет назад +369

    (a+b)² = a²+b²
    I was questioning reality for a second XD

    • @btdpro752
      @btdpro752 5 лет назад +6

      Same

    • @neilgerace355
      @neilgerace355 5 лет назад +6

      That's actually good science. Always question what everyone thinks reality is:)

    • @TheDslide
      @TheDslide 5 лет назад +11

      @@neilgerace355 agreed but it can drive u mad if u do it too much

    • @yrcmurthy8323
      @yrcmurthy8323 5 лет назад +8

      Accepts when a or b = 0

    • @keescanalfp5143
      @keescanalfp5143 5 лет назад +2

      @@TheDslide, yes, you were rapid, a second could be long enough.
      reality exists, well can be said to exist, thanks to your recognising truth about it, and thanks to your recognising the lies too.
      as to what everyone thinks about it, some of us had as a first thought drawing a / through the = .
      great clickbait for math lovers.

  • @fluffymassacre2918
    @fluffymassacre2918 5 лет назад +256

    Breaking news: BlackpenRedpen loses all of its subscribers after saying that (a+b)^2=a^2+b^2.

    • @neilgerace355
      @neilgerace355 5 лет назад +8

      They didn't try it for themselves first, so they haven't listened what bprp always says :)

    • @blackpenredpen
      @blackpenredpen  5 лет назад +13

      Fluffy Massacre hahahahaha

  • @therealAQ
    @therealAQ 5 лет назад +144

    I almost had a stroke at the beginning D:

  • @arequina
    @arequina 5 лет назад +13

    I love how you explain this in such a layman's term.

  • @gradecracker
    @gradecracker 5 лет назад +10

    I LOVE how you take a break from calculus to appreciate the humble Algebra! You have truly opened my mind to appreciate algebra once again!!! Cannot thank you once again since I am a regular viewer. YOU NEVER DISAPPOINT!!!!!

  • @Bloble25
    @Bloble25 5 лет назад +34

    I really like how you explain theorethical math to a huge variety of people and I think everyone can understand it and not only those who did it in school alread. I think it´s really nice to learn new things even if you don´t need it in most cases because we train our brains with this and your love for math makes it even better to understand and makes me happy aswell.
    Great job keep up the work!

    • @MathPhysicsEngineering
      @MathPhysicsEngineering 2 года назад

      For those who are intrested to see a rigorous proof of the theorem, with detailed explanation of every step check a video
      on my channel called:
      Calculus 1: The Binomial Expansion Formula Derivation and Proof
      it is a part of the calculus playlist that I'm recording

  • @hmmmm3094
    @hmmmm3094 Год назад +2

    thank you for this. I am trying to stop just mugging formulas my teacher is feeding me and trying to understand how formula is found. You are one of the only videos explaining derivation in so much detail. 🙏

  • @tsurutuneado5981
    @tsurutuneado5981 5 лет назад +52

    2ab: "Am I a joke to you?"

  • @BabyXGlitz
    @BabyXGlitz 5 лет назад +10

    also the the sequence 1 2 1 is the number of vertices you span when travelling diagonally from a vertex to the opposite vertex in a square. as a matter of fact each row in pascal's triangle represents an n-dimensional cube, so 1+5+10+10+5+1 = 32 or 2^5 or the number of vertices of the 5-dimensional cube.

  • @jordantyler148
    @jordantyler148 5 лет назад +55

    I thought it was April fools for a second

  • @sanelprtenjaca9776
    @sanelprtenjaca9776 5 лет назад +11

    This video is so educative. Pascal's triangle, factoriels, sign for summation, combinatirics and powers in one video...

    • @blackpenredpen
      @blackpenredpen  5 лет назад +3

      Sanel Prtenjača yea, this had so much and I was so excited to record 3 parts all in one day!!

  • @GaryTugan
    @GaryTugan 5 лет назад +2

    Haha! you got me....I was so stunned I actually PAUSED the video 2 seconds after you wrote (a+b)^2 = a^2+b^2.... wondering what the heck had happened. Also scrolled down expecting to see a plethora of haters in the comments! So, I was quite surprised at the comments, and realized that I needed to watch more of the video before being surprised :) I really dig your humor! And it's not even April Fools Day....

  • @shuddhoshawttoroy6257
    @shuddhoshawttoroy6257 2 года назад +2

    Very nice and healthy lecture, helped me to conquer my syllabus, which was looking very difficult in my study material. Thanks Sir.

  • @pilifx
    @pilifx 5 лет назад +4

    Oh wow. This brings back long forgotten memories of high school. Thank you for yet another incredibly entertaining video

  • @sebaseba285
    @sebaseba285 5 лет назад +37

    I learned more in the first minute than 5 yrs of high school

  • @nadream_nadr34m
    @nadream_nadr34m 5 лет назад +4

    Pulled a switcheroo with that first bit. My complex roots were quaking right there.

  • @JoshuaHillerup
    @JoshuaHillerup 5 лет назад +1

    I got so confused why you were covering this since I learned it when I was in grade 11, but then I remembered my highschool education was very weird compared to most places and isn't even taught that way here anymore.

  • @thenewguy7527
    @thenewguy7527 5 лет назад +2

    You should do a^n + b^n or a^n - b^n next

  • @huntforerror
    @huntforerror 5 лет назад +1

    (a+b)^2 = a^2 + b^2 was too uncomfortable to watch. I had to cover it until you erased it. Thank you for not torturing me too long.

  • @smoughlder5549
    @smoughlder5549 5 лет назад +39

    (a+b)^2 DOES equal a^2 + b^2 though...
    ...in a commutative ring of characteristic 2

  • @bailey125
    @bailey125 5 лет назад +1

    You need a completely different approach for fractional and negative powers. It's an infinite series where the answer is the sum. If you have (a+bx)^k, you need to convert it to the following (a^k)(1+(b/a)x)^k and then the nth term is (a^k)+(a^k)[ ((k)(k-1)(k-2).....(k-n)(x^n)) / n! ]

  • @awertyuiop8711
    @awertyuiop8711 5 лет назад +52

    If n is not a positive whole number, it should still be possible to apply the theorem, we just have to
    「do more work」
    (Limits flashbacks intensifies)

    • @blackpenredpen
      @blackpenredpen  5 лет назад +7

      Hahaha, nice one!!! And that's part 2 btw.

  • @toqa002
    @toqa002 5 лет назад +12

    OH MY GOODNESS WAIT......
    I'M SUFFERING OF TRYING TO UNDERSTAND THIS THEORY AND YOU'RE......
    JUST MUCH THANKS 😭😭😭❤❤❤❤❤❤❤❤❤
    I LOVE YOU REALLY 😹😭❤💛💜🌻

  • @vasundarakrishnan4093
    @vasundarakrishnan4093 4 года назад +3

    0:12 look at him smiling at our confusion

  • @nikhilnagaria2672
    @nikhilnagaria2672 3 года назад

    0:22 oh I loved those Dr Peyam clips, I remember watching this :D

  • @waywalker713
    @waywalker713 5 лет назад +1

    Very Good explanation!!!!

  • @emilvincent5034
    @emilvincent5034 4 года назад

    The illustration you show in the beginning is very helpful but it can be explained much easier by using mathematics of the vedic to illustrate

  • @paulasilva7092
    @paulasilva7092 4 года назад

    La mejor explicación que he escuchado

  • @pratikmaitra8543
    @pratikmaitra8543 5 лет назад

    TS 5:00...very important and oft missed point. You sir are really doing the lord's work here. One of the bwst maths channel out there on youtube.

  • @samihenrisub7i997
    @samihenrisub7i997 5 лет назад +12

    Fun fact : Pascal's triangle gives the powers of 11

    • @anusheelsolanki1
      @anusheelsolanki1 5 лет назад +2

      Only till the 4th row

    • @leadnitrate2194
      @leadnitrate2194 4 года назад +1

      @@anusheelsolanki1 no, it does for all rows. Consider 1 4 6 4 1.when we call it a power of 11, what we really mean is (1×10^4 + 4×10^3 + 6×10^2 + 4×10^1 + 1×10^0) is a power of 11.
      Now consider row 5. The number here is
      1 5 10 10 5 1. If you do the same (convert it into decimal), it becomes
      (1×10^5 + 5×10^4 + 10×10^3+ 10*10^2 +5×10^1 + 1×10^0) which is 161051, which is a power of 11.

    • @nalat1suket4nk0
      @nalat1suket4nk0 3 года назад

      @@anusheelsolanki1 nope

    • @nalat1suket4nk0
      @nalat1suket4nk0 3 года назад

      Only if you take by decimal expansion, row 5, 1 5 10 10 5 1
      1*100000+5*10000+10*1000+10*100+5*10+1*1=11^5
      Explanaiton: so because each row can be expressed as binominal expansion, let a=10 and b=1
      Then (a+b)^n=(10+1)^n=11^n

    • @nalat1suket4nk0
      @nalat1suket4nk0 3 года назад +1

      A lot of patterns appear in pascals triangle like the sun are powers of 2, the fibonnaci sequence appears in the sum of special diagonals, serpeinski's triangle with odd/even, some patterns that are close to serpeinski's triangle appear with multiples of other numbers, 3, 4, 5,... The (real) diagonales show the triangular(2D), tetrahedron (3D triangle), pentatope (4D triangle),... And pascals triangle can be written as combinatorics,... A lot of same patterns appear in higher dimensions of pascals triangle, pascal simplexes

  • @justabunga1
    @justabunga1 5 лет назад +1

    Wow, I remember this. We can use this to derive the definition of the derivative using this formula for power rule.

    • @blackpenredpen
      @blackpenredpen  5 лет назад +1

      Justin Lee
      Yes. And we can also write e as a series.

  • @qwertyyoe3334
    @qwertyyoe3334 4 года назад

    You are the best teacher

  • @gavinf.9778
    @gavinf.9778 3 года назад

    Learning this rn in gr12 data management

  • @mayanksood4709
    @mayanksood4709 5 лет назад

    Please::
    A pyramid with a square base, 4 m on each side and four
    equilateral triangular faces, sits on the level bottom of a lake at
    a place where the lake is 10 m deep. Find the total force of the
    water on each of the triangular faces.

  • @simonekentish7491
    @simonekentish7491 3 года назад +1

    Here’s the deal... your video was helpful and fun. Subscribed!

  • @rith359
    @rith359 4 года назад

    I like this
    Insert: good lighting

  • @1willFALL
    @1willFALL 5 лет назад +2

    With the music and the way you said this is very easy, I almost believed you...

  • @Muck-qy2oo
    @Muck-qy2oo 2 года назад +1

    That's really well explained! Thanks!

  • @mayanksood4709
    @mayanksood4709 5 лет назад

    Answer this please.
    A pyramid with a square base, 4 m on each side and four
    equilateral triangular faces, sits on the level bottom of a lake at
    a place where the lake is 10 m deep. Find the total force of the
    water on each of the triangular faces.

  • @MK-13337
    @MK-13337 5 лет назад

    (a+b)^2 = a^2 + b^2 in certain cases (for example some modular arithmetic structures, or in vector analysis when a and b are perpendicular)

    • @blackpenredpen
      @blackpenredpen  5 лет назад

      Matti Kauppinen mod 2

    • @MK-13337
      @MK-13337 5 лет назад

      @@blackpenredpen And I think (a+b)^2 = a^2 + b^2 if ab =0 mod n (so for example mod ab, or if a=xy then xb or yb does it. edit: one of our abstract algebra homework questions was about proving a similar result to this but I forget the details)

  • @jonathangrey6354
    @jonathangrey6354 5 лет назад

    Please let this be a new series.

    • @blackpenredpen
      @blackpenredpen  5 лет назад +1

      Nole Cuber
      Yes. We will totally get a “series” out of this
      Btw, part 2 is already in description

    • @papapapapapapageno
      @papapapapapapageno 5 лет назад

      @@blackpenredpen pun intended;)?

  • @janernn
    @janernn 5 лет назад +10

    I was a bit stressed out until he crossed out a²+b²
    Edit: @ 12:43, when you've written n! = n*(n-1)*...*3*2*1, strictly speaking it will only be correct for n >= 5 right?

    • @rastaarmando7058
      @rastaarmando7058 5 лет назад

      n = 1,2,3....

    • @phobos3898
      @phobos3898 5 лет назад +2

      No not nessicarily, n just has to be greater then one. He just wrote that for the example, it can also be written as n!=n*(n-1)*...*1

    • @akshataggarwal4002
      @akshataggarwal4002 4 года назад

      @@rastaarmando7058 u didn't understood the joke sir!

  • @mikehoffman8638
    @mikehoffman8638 4 года назад

    Thank you for good math video.

  • @quitzechavez2299
    @quitzechavez2299 5 лет назад +2

    Man you should do a video about polynomial theorem

    • @blackpenredpen
      @blackpenredpen  5 лет назад +1

      Quitzé Chávez
      Part 3 is about trinomial. And that pretty much it.

  • @muhammadqasim7056
    @muhammadqasim7056 5 лет назад

    Derivation of cycloid's area through integration next please .love the videos ,even if i cant understand some of them,cheers.

  • @hypnovia
    @hypnovia 5 лет назад

    MY HOMEWORK WAS ON THIS TODAY, YOU SAVED ME

  • @yuvrajsinghraj
    @yuvrajsinghraj 5 лет назад +10

    Bprp-(a+b)²=a²+b²
    Me-Nani?

  • @adityakarki4663
    @adityakarki4663 5 лет назад +1

    Hello...sir you are great...
    Love from india....

  • @akoskulcsar350
    @akoskulcsar350 5 лет назад +1

    Finally a video I can understand and already know the solution of! Haha

  • @manikandan-tf9un
    @manikandan-tf9un 4 года назад

    Very good Explanation BUD

  • @sofianemohammed8046
    @sofianemohammed8046 5 лет назад +5

    Please calcul the integral from 0 to π/2 of tan(x) 🙏

    • @alexwhite9550
      @alexwhite9550 5 лет назад +5

      Diverges

    • @justabunga1
      @justabunga1 5 лет назад

      The answer goes to infinity, so it diverges. You can try checking it on your graphing calculator as fnInt(tan(x),x,0,pi/2), but the answer will show up as error, tolerance not met, or whatever answer it says there.

  • @danielwimmer4698
    @danielwimmer4698 5 лет назад

    So, when you have a certain number of x's and a certain number of y's (partitions of n of course) you have multiple ways of representing that only because there are multiple x's and y's not because the position of those x's and y's matters obviously. Combinations are literally just pairings of n elements into unique sets of size k hence n choose k. Although, in the case of the binomial theorem the size of the set is always n you simply choose k out of n elements to be different; x not y or the other way around.

    • @justabunga1
      @justabunga1 5 лет назад

      Yep, that's correct. Some people confuse this with permutations. Both permutations and combinations are different due to the ordering. If you're trying to find this on your calculator, the formula that he wrote in this video is denoted as nCr, which is n!/(r!(n-r)!). Permutation is denoted as nPr, which is n!/(n-r)!. n and r must positive integers. 0!=1 by definitely of the empty set.

  • @Whateverbro24
    @Whateverbro24 5 лет назад

    Such an amazing video❤️❤️, please do more videos on combinatorics and discrete mathematics.

  • @abdulrahmanjouda9850
    @abdulrahmanjouda9850 5 лет назад

    Can you explain Laplas transfer?
    And thanks for you for all your videos.. Everyone watching you love learn and love you
    Thank you again 🖤

  • @IISH4RKZzII
    @IISH4RKZzII 5 лет назад

    Thank you
    Cant wait for the general formula

    • @blackpenredpen
      @blackpenredpen  5 лет назад +1

      Its in the description now. You can have n being -2

  • @protoword10
    @protoword10 5 лет назад +1

    I remember me learning that in high school!

  • @eatdacarrot1311
    @eatdacarrot1311 5 лет назад

    this blew me away

  • @giovannimariotte4993
    @giovannimariotte4993 4 года назад

    We want more aboht this issue

  • @AndDiracisHisProphet
    @AndDiracisHisProphet 5 лет назад +7

    almost as good as 3

  • @yrcmurthy8323
    @yrcmurthy8323 5 лет назад +4

    I studied this last year, 7th class

    • @yrcmurthy8323
      @yrcmurthy8323 5 лет назад

      Thank for the heart sir, @blackpenredpen

  • @lumina_
    @lumina_ Год назад

    helpful review, thank you :)

  • @davidadegboye773
    @davidadegboye773 5 лет назад +2

    0:20 thank you so much I almost had a heart attack

  • @beri4138
    @beri4138 3 года назад

    I feel like I understand everything in your videos and then I look at my homework and cry

  • @notafeesh4138
    @notafeesh4138 4 года назад

    I love Pascal’s Triangle... 😁

  • @JanickGers0
    @JanickGers0 5 лет назад

    I would love a video about finding the inverse function of a cubic, for example f(x)=x^3-x^2

    • @justabunga1
      @justabunga1 5 лет назад

      Your example answer for this doesn’t have the actual answer for the inverse function since we cannot solve for y if you said x=y^3-y^2.

    • @JanickGers0
      @JanickGers0 5 лет назад

      @@justabunga1 It does have an answer, it's just that the procedure to get there is very tedious using the cubic formula. I want to know if there's something else I can do here.

    • @justabunga1
      @justabunga1 5 лет назад

      JanickGers0 it does, but can you try solving for y?

    • @elskx443
      @elskx443 11 месяцев назад

      @@justabunga1Cartesian plane and graphing last in line?

  • @Aj-kj6wn
    @Aj-kj6wn 5 лет назад

    Next pick up multinomial for negative index

  • @blueberry1c2
    @blueberry1c2 5 лет назад

    0:20 good save i almost had a stroke

  • @nicholasleclerc1583
    @nicholasleclerc1583 5 лет назад

    0:00
    I-I-Is that... the Overwatch theme ?
    *_W O O O O O W ! ! ! ! !_*

  • @melaniem2965
    @melaniem2965 4 года назад

    When you said a^2+b^2=(a+b)^2, I was about to ring up the local exorcist to see if you were possessed, fortunately I kept watching

  • @hnnagarathna7286
    @hnnagarathna7286 4 года назад

    Wish u were my maths teacher

  • @MathPhysicsEngineering
    @MathPhysicsEngineering 2 года назад

    For those who are intrested to see a rigorous proof of the theorem, with detailed explanation of every step check a video
    on my channel called:
    Calculus 1: The Binomial Expansion Formula Derivation and Proof
    it is a part of the calculus playlist that I'm recording

  • @GameMaster-pz9pw
    @GameMaster-pz9pw 5 лет назад

    Hey, I was wondering if you could do a video on the cubic formula, or just a way in general to solve cubic equations. I've been confused about this and haven't been able to find any videos that are easy to understand.
    Thanks!

  • @Andreas4696
    @Andreas4696 5 лет назад

    Can you make a video on the Laplace transfer?

  • @Ceorolus
    @Ceorolus 4 года назад

    As most of us know, this is very easy.

  • @syedrizvi2687
    @syedrizvi2687 3 года назад

    Thanks a lot!

  • @faastex
    @faastex 5 лет назад +3

    I seriously started questioning my entire mathematical knowledge in the first 30 seconds of the video...

  • @fongleopard6462
    @fongleopard6462 Год назад

    Hello blackpenredpen.
    Why zero can't be used when applying binomial expansion to evaluate (1.01)4.
    I know this is easy when we express (1.01)⁴ as (1+ 0.01)⁴.
    Suppose we wish to express (1.01)⁴ as (0 + 1.01)⁴. Why this gives zero as a answer.

  • @plislegalineu3005
    @plislegalineu3005 2 года назад

    3:51 well that six made me like 😳
    I thought there will be a four

  • @weihungchew8228
    @weihungchew8228 5 лет назад +1

    Sir,can u give an explanation about why volume formula can use disk method ,but surface area we cannot use cylinder to approximate instead of frustum since it is infinite cylinder

  • @jayveeflores7757
    @jayveeflores7757 5 лет назад +2

    Hiii im kinda new to this channel you seem really awesome and I kinda understand your lessons. I was just wondering if you have videos or are you planning to make videos tutoring basic calculus. And if you do, do you have a playlist for it. I'm still a freshman trying to go for engineering course thank youuu

    • @blackpenredpen
      @blackpenredpen  5 лет назад

      Jayvee Flores hi Jayvee and welcome !! Please see my description for my website and other resources. Thanks and hope you enjoy my content here

    • @jayveeflores7757
      @jayveeflores7757 5 лет назад

      @@blackpenredpen Thank youu! Keep making videos your content is very awesome I am looking forward for more of your videos. Best wishes

  • @Patapom3
    @Patapom3 5 лет назад

    Amazing!

  • @captainch371
    @captainch371 2 года назад +1

    maybe youtube was listening during my math class today?

  • @AlessandroZir
    @AlessandroZir 3 года назад

    omg! this was very useful; thanks a lot; 🤸🙌🧘💕💕

  • @eugen5343
    @eugen5343 5 лет назад +1

    Thanks for your great job! Could you please make video about Multinomial theorem (x1+x2+x3+x4+...+xm)^n. Thats would be wonderful, isn't it?

  • @hotroadcol4166
    @hotroadcol4166 5 лет назад

    Thanks

  • @lukas3437
    @lukas3437 4 года назад

    Thank you for sooo a great video :)

  • @ogorangeduck
    @ogorangeduck 5 лет назад

    just did this combined with proof by induction for a test on this

  • @froylanperez1654
    @froylanperez1654 5 лет назад +1

    Lmao, he included the sphere graphic from that triple integral video 😂

  • @asgardianguy178
    @asgardianguy178 4 года назад

    You are amazing

  • @MTW144
    @MTW144 4 года назад

    Woooow amazing

  • @subhendudas3022
    @subhendudas3022 5 лет назад

    Dear blackpenredpen,
    Look at 6:49. I found it interesting when I was looking at the rows only. The first row contains 1=(11^0), (here n=0),
    2nd row contains 2 digits 1 and 1 to make it 11=(11^1),(here n =1),
    3rd row contains 3 digits 1,2 and 1 to make it 121=(11^2),(here n=2),
    4th row has 1,3,3,1 to make 1331=(11^3),(n=3),
    5th row is 14641=(11^4),(n=4) and so on
    . Is it a coincidence to get 11's powers raised to n value every time?

    • @michaeldamolsen
      @michaeldamolsen 5 лет назад

      I does get a little more awkward when you have two digit numbers in the triangle, but if you carry to the right it still works.
      You want to know why? Here is a tip on how to get started on the answer: 11^n = (10 + 1)^n
      If you need another tip: expand the above using the Binomial Theorem :)
      You might also notice that each row sums up to 2^n, wonder why?

    • @subhendudas3022
      @subhendudas3022 5 лет назад +1

      Each row sums up to 2^n. That easy to understand because expansion of (1+x)^n gives that result when x=1. That gives as sum of co officiants as 2^n.
      Okky now I understand both of your statements. Thank you.

  • @GameMaster-pz9pw
    @GameMaster-pz9pw 5 лет назад

    (a+b)^2=a^2+b^2 works if a=0 and b=0.

  • @user-wu8yq1rb9t
    @user-wu8yq1rb9t 2 года назад

    Thank you Teacher
    *bP🖋️rP🖍️* ❤️

  • @atheerarrak80
    @atheerarrak80 3 года назад

    Thanks mann

  • @neilgerace355
    @neilgerace355 5 лет назад

    15:30 We will get there eventually!

  • @ProfessordeMatemáticaMarcioFre

    Tem algum vídeo demonstrando a fórmula do polinomio de leibniz .

  • @michawielgus9827
    @michawielgus9827 5 лет назад

    a^n+b^n
    easy

  • @awertyuiop8711
    @awertyuiop8711 5 лет назад +2

    I've got an "unnecessary" but potentially interesting question:
    How about a theorem for the nth power of any polynomial?
    (a+...+b)^n
    Cheers!

    • @blackpenredpen
      @blackpenredpen  5 лет назад +1

      Awer Tyuiop see part 3: ruclips.net/video/xrE3rgkBTPA/видео.html and we can go from there