Sigma notation for sums | Sequences, series and induction | Precalculus | Khan Academy

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  • Опубликовано: 9 сен 2024

Комментарии • 380

  • @pandamoniumxP
    @pandamoniumxP 9 лет назад +791

    The way you wrote the sigma symbol was chillingly perfection.

    • @LearnMathsFree
      @LearnMathsFree 9 лет назад +18

      +Jessica I agree, he has nice sigmas.

    • @starwarfan8342
      @starwarfan8342 6 лет назад +6

      Lol I can never draw it right.

    • @bhavyadesai6528
      @bhavyadesai6528 5 лет назад +11

      Ligma ~ Sigma 😂

    • @tfist
      @tfist 4 года назад +2

      thanks to this video i finally understand Sugma meme

    • @hooligan.hernan
      @hooligan.hernan 4 года назад +3

      Jessica we are witnessing perfection.

  • @notandinotandi123
    @notandinotandi123 9 лет назад +922

    Sooo.. it's basicly a FOR loop? Nice!

    • @joemm96
      @joemm96 9 лет назад +176

      Finni M. programmers unite!!!

    • @TheVerbalAxiom
      @TheVerbalAxiom 8 лет назад +19

      +Finni M. Code

    • @DanielH212MC
      @DanielH212MC 8 лет назад +11

      +Finni M. Yup!

    • @DanielH212MC
      @DanielH212MC 8 лет назад +17

      +Finni M. It's a for loot except you cannot control by what increment the loop's index increases by, it's always 1. However, if you don't use the index in the looped part, but a multiple of it, the porblem can easily be solved, like I did in a random pi calculation formula from pi = 3 + 4/(2*3*4) - 4/(4*5*6) + 4/(6*7*8) - 4/(8*9*10)... = sigma x = 1 to infinity (6/(64x^4 - 20x^2 + 1))+3

    • @LMAO-ef3ip
      @LMAO-ef3ip 8 лет назад +5

      +RaZe Shot code is not life, the real life you should live is beyond your computer screen...

  • @Moccasinmike
    @Moccasinmike 2 года назад +101

    Why can't teachers explain things this clearly?! Thank you!

  • @solo9363
    @solo9363 6 лет назад +169

    My Calculus teacher didn’t explain these and we have a test with them on it today. Thanks for this guide it was easy to understand and now I feel like I understand it entirely.

  • @EmotionxPlayOw
    @EmotionxPlayOw 6 лет назад +179

    When you search for the lesson you don't understand on RUclips and multiple videos come up but you choose to watch Khan Academy.

    • @divyanshsinghtariyal9485
      @divyanshsinghtariyal9485 5 лет назад +2

      Potatsu no . unacademy is way better

    • @coleschemistrychannel4172
      @coleschemistrychannel4172 4 года назад +2

      Divyansh TM you’re here, aren’t you?

    • @ayushburman1459
      @ayushburman1459 4 года назад +4

      @@divyanshsinghtariyal9485 Lol its not even closer

    • @divyanshsinghtariyal9485
      @divyanshsinghtariyal9485 4 года назад

      Padhai Lelo! it is better if you are doing higher studies like me.Not 8th,9th or 10 th grade maths and physics like you

    • @ayushburman1459
      @ayushburman1459 4 года назад +5

      @@divyanshsinghtariyal9485 Kid and can you even differentiate between a non-profit organisation and bunch of money sucking bastards and 11th and 12th grades aren't higher studies Lmao..

  • @fusion325
    @fusion325 3 года назад +8

    oh my god! index was the key word here, I couldn't understand this at all for the entirety of math class today but when watching this video my brain instantly connected the word index with a loop in java and I instantly understood the concept. Geez, it's funny how fast you can catch onto something once the right words are presented

  • @bigbad123321
    @bigbad123321 5 лет назад +34

    I learned more watching this video than a 1hr 40min tutorial I had yesterday. Thanks

    • @nohackers2037
      @nohackers2037 5 лет назад +3

      IKR! I haven't even studied series (Well I have but not in depth at almost collage level) and now I feel 100% smarter than all students in my class. This guy is the best!

  • @muscleman3515
    @muscleman3515 4 года назад +14

    Khan Academy would legit make any math problem look super easy in their tutorials! 10/10👋🏼

  • @ramelm5004
    @ramelm5004 8 лет назад +13

    float sum;
    for(int i = 1; i

  • @ThienNguyen-ph4rv
    @ThienNguyen-ph4rv 10 лет назад +69

    Thanks, these videos are saving my grades from the wrath of my crappy algebra 2 teacher.

  • @thorstambaugh1520
    @thorstambaugh1520 5 лет назад +39

    I added the second series in 10 seconds. The numbers can be paired off to sum 100 1 and 99, 2 and 98, etc. There are 49 pairs plus 50 plus 100 totaling 5050. This may be done for any series with any standard linear increment

    • @mitcigamer4289
      @mitcigamer4289 4 года назад +3

      thx, that really helped!😊😊😊

    • @edenofeknalian6846
      @edenofeknalian6846 4 года назад +5

      wow. we have a gauss on out hands ladies and gentlemen.

    • @firezone5163
      @firezone5163 4 года назад +4

      Genius ;)

    • @nishkarshverma2020
      @nishkarshverma2020 9 месяцев назад

      this method simplified is wht arithmetic progression indeed is

  • @Rae4475
    @Rae4475 9 лет назад +17

    You're the man Sal!

  • @fridahmadiba1891
    @fridahmadiba1891 8 лет назад +6

    this video has been very helpful. thank you

  • @bendauber9200
    @bendauber9200 6 лет назад +18

    Is it weird that even though I use the website I still make sure to find and like the youtube video because its so amazing?

  • @iVince905
    @iVince905 10 лет назад +10

    Perfect timing. Just learning this now

    • @iVince905
      @iVince905 3 года назад

      @andyr roopram No, only needed it to pass a midterm. Don't remember any of this tbh lol

    • @slouchysenpai1970
      @slouchysenpai1970 3 года назад +2

      @@iVince905 wow u r still alive

    • @iVince905
      @iVince905 3 года назад

      @@slouchysenpai1970 haha yes, I lost my life in uni but I resurrected

  • @bludgeon1081
    @bludgeon1081 3 года назад +12

    And then God said: "Let there be Math!"

    • @alezvolta
      @alezvolta 3 года назад +1

      Hey, Vsauce! Michael here; math is a tool that most professionals use, and it's a great thing that we discovered it.
      Or did we?
      *Vsauce music plays*

  • @colinwhitlock5148
    @colinwhitlock5148 6 лет назад +15

    Teacher literally said to learn this part ourselves when we had 15 minutes of class left at the end.

  • @odb-yl9om
    @odb-yl9om 6 лет назад +8

    makes it sound so easy!

  • @melissapatton7359
    @melissapatton7359 7 лет назад +7

    This is so helpful. We use Prentice Hall textbooks at my school and they're basically worthless for explaining how to do problems. I've missed two days of Algebra 2 in a row and this video just brought me some hope. Thanks!

  • @leadseducators-leoshe5401
    @leadseducators-leoshe5401 6 лет назад +2

    Salam,
    I am littely crying after watching this video..... trust me i have studied over 20 uears in colleges n unis but none had explained it so..... please keep tuting us all and maintain your contribution to develop humans.....

  • @ellaartenstein853
    @ellaartenstein853 9 месяцев назад +1

    Thank you it’s very concise and helpful

  • @RobinSingh-ms3zt
    @RobinSingh-ms3zt Год назад +1

    Thanks for this wonderful explanation.

  • @millerscottie1688
    @millerscottie1688 10 лет назад +5

    OMG!!!! U ARE GENIUS ^~^

  • @abhilashasinha5186
    @abhilashasinha5186 Год назад +2

    one equation is (i(i+1))/2 for sigma notation

  • @Nexaeon
    @Nexaeon Год назад +1

    Thnx you so much I really understand

  • @reminderIknows
    @reminderIknows 4 месяца назад +1

    local count = 0
    for i = 1, 100 do
    count += 1
    end
    print(count)
    count = 0
    for i in range(1, 100):
    count = count + i
    print(str(count))

  • @user-dt8eu9wy9v
    @user-dt8eu9wy9v 3 года назад +2

    What is the sigma notation of 10 + 30 + 130 + 630 +3130?

    • @17honhathong56
      @17honhathong56 2 года назад

      I'm sorry for being late, but If you're still interested, here's how it can be solved:
      Noticed the sequence 10 + 30 + 130 + 630 + 3130, when you subtract each number to the number before it, the increment of the sequence is:
      u1 = 10
      u2= u1 +20
      u3= u2 + 100
      u4= u3 + 500
      u5= u4 + 2500
      ->Now, we have the sequence of 20, 100, 500, 2500 (just ignore the u1 or the "10" because it doesn't have the property of the sequence), we can write it down as 20.5^x (for x=0 to 3)
      Back to the original sequence, you can break it down as:
      10 + (10 +20) + (10+ 20 +100) + (10 + 20 + 100 + 500) + (10 + 20 + 100 + 500 + 2500)
      5.10 + 4.20 + 3.100 + 2.500 + 1.2500
      (v1) (v2) (v3) (v4) (v5)
      See how it all come together?
      ->Now, we can craft the function
      For sigma (x=0 to 3), {the reason for this is we only take the sum from v2 to v5}
      we have ((3-x).(20.5^x))
      Don't forget to bring back 5.10 (v1) to the sum as we have left it out.
      => 3930

    • @isavenewspapers8890
      @isavenewspapers8890 4 месяца назад

      ​@@17honhathong56 I really like the math in this reply, but I think the original comment was asking for a sum where 10, 30, 130, 630, and 3130 are the terms. I believe I have found such a sum, which I will share shortly.

  • @yaquanliang4994
    @yaquanliang4994 6 лет назад +15

    Hey may I ask does the 'i' and 'n' represent the same thing? thanks in advance!

    • @bginer-chess2154
      @bginer-chess2154 4 года назад +5

      Yes

    • @XBGamerX20
      @XBGamerX20 3 года назад

      you just give the solution of the variable like in an equation

  • @gabilovesinging8987
    @gabilovesinging8987 5 лет назад +1

    Wow thankyou sm... I'm some one who has a lot of problems in maths but after seeing this i'm def done w sigma notation ....wow you guys should try ITS AMAZING

  • @melan6bits321
    @melan6bits321 7 лет назад +1

    Best academy for IT students thanks ...

  • @jd-ju3vr
    @jd-ju3vr 6 лет назад +2

    your handwriting is so beautiful

  • @x86_architecture10
    @x86_architecture10 2 года назад +1

    Thanks for making this video. I see this sigma symbol all over Wikipedia, but I never knew what it meant until now.

  • @millerscottie1688
    @millerscottie1688 10 лет назад +6

    Khan is credit to my know ledge!!!!!!!!

  • @daijoubu4971
    @daijoubu4971 4 года назад +2

    RUclips teaches me more than actual teachers. Idk whether it's good or bad 🤷

    • @tuluppampam
      @tuluppampam 3 года назад

      It's good for students, it's bad for teachers

  • @notjared3667
    @notjared3667 4 года назад +1

    6 years ago and still useful Thanks!

  • @ellispiper6313
    @ellispiper6313 2 года назад

    froget all my alebra and never even took precalt, which are needed for uni stats. Thank you sir, the math aspect is all making sense

  • @HabibKhan-ft4ik
    @HabibKhan-ft4ik 3 года назад +1

    Oo oo😯 i don't believe that i will get my answer in 2 minutes

  • @CM-hn6oc
    @CM-hn6oc 5 лет назад +1

    Oh my god this is awesome 🎉🎊🎆🎇🎍🎄🎄🎄🎖️🎖️🎊🎆🎇🎉

  • @melainamathgenius5068
    @melainamathgenius5068 8 лет назад +3

    Awesome math teacher!

  • @ironcyr3157
    @ironcyr3157 3 года назад +1

    math is amazing

  • @mariuswilsch4035
    @mariuswilsch4035 2 года назад +1

    Is this kinda the math version of a while loop and incrementing a variable up to a certain threshold?

  • @rajeshfilmytalks7682
    @rajeshfilmytalks7682 6 лет назад +4

    we need to read it summation

  • @thesalmonfish3891
    @thesalmonfish3891 2 месяца назад

    Wow it's rely that simple

  • @LaussseTheCat
    @LaussseTheCat 9 месяцев назад

    I don't even want to do mathematics as a career and I LOVE sigma notation

  • @kenlaw7505
    @kenlaw7505 4 года назад

    Extremely clear of the explanation, even better than my college teacher. BTW Love your voice

  • @chanuthgunawardene7579
    @chanuthgunawardene7579 5 лет назад +1

    WOW, I didn't realise thanks!

  • @ThomasGiles
    @ThomasGiles 10 лет назад +6

    Cool. So can you do stuff like multiplying at each iteration instead of adding?

    • @DrEnginerd1
      @DrEnginerd1 10 лет назад +1

      That is done through capital pi notation, you can google that if youd like

    • @ThomasGiles
      @ThomasGiles 10 лет назад

      Cameron Belt Cool. I wonder why it's called capital Pi, when that greek letter is already used?

    • @DrEnginerd1
      @DrEnginerd1 10 лет назад

      Yep, its called capital pi notation, probably a whole different subject, but it exists

    • @paradoxica424
      @paradoxica424 10 лет назад +1

      The Capital Pi means the product of a series, which you wanted. It follows the same method of being written out.

    • @prime2836
      @prime2836 2 года назад

      r u alive?

  • @rampranavnavendran8330
    @rampranavnavendran8330 6 лет назад +1

    THXXXXXX

  • @John010
    @John010 3 года назад

    this instantly came to mind:
    for(int i = 0;i < 100;i++)

  • @animateforfun4799
    @animateforfun4799 Месяц назад

    this is really helpful! Thanks!

  • @pepper4335
    @pepper4335 Месяц назад +1

    what a sigma!!!

  • @cosmicdarkmatter1128
    @cosmicdarkmatter1128 Год назад

    That was the best explanation that I've ever seen. Thanks

  • @MyteeT
    @MyteeT 4 года назад

    THANK YOU SO MUCH NOW I'LL DO GOOD IN TOMORROWS EXAM.

    • @roku2887
      @roku2887 4 года назад

      Mytee how’d you do on your exams?

  • @aniket_mast_admi
    @aniket_mast_admi 5 лет назад +1

    Great explaination.😄😄😄

  • @VeryHappyCat
    @VeryHappyCat 7 месяцев назад

    Thanks you made sigma feel easy

  • @smartscience5305
    @smartscience5305 3 года назад +2

    I am 12 years old and I finished learning quantum physics, and learning calculus and topology in string theory 😊😊😊😊🌍🌍🌍🌍🌍🌍🌍

    • @FTBW.17
      @FTBW.17 3 года назад

      How and what are the resources ?

    • @_Yoshikage_Kira
      @_Yoshikage_Kira 3 года назад +1

      And yet you didn't knew about summation

    • @ian.ambrose
      @ian.ambrose 2 года назад

      Lmao. I'm 8 and got a phd Havard here. It's been pretty easy for me. You should go home and study more, we don't accept such failure.

  • @victorsfirm9525
    @victorsfirm9525 4 года назад

    sir let me remind you something that you have forgot. there are people who cant't understand by the time your are doing your best but let me encourage you to the max please do you best to get those people in your box

  • @user-ti5em6mr2x
    @user-ti5em6mr2x 4 года назад +1

    I just mastered it like a pro

  • @jeffmutt2457
    @jeffmutt2457 5 лет назад

    Hi there I am amazed by the tutorial...

  • @daxtronmax2936
    @daxtronmax2936 3 года назад

    Thank you,i Will understand it easy-ly

  • @suvangoda7773
    @suvangoda7773 4 года назад

    Ahhhh this was a lifesaver. Tysm

  • @yohantv3570
    @yohantv3570 4 года назад

    This is good information! Thanks for explaining.

  • @Moon-x3t
    @Moon-x3t Год назад

    Wonderfully explained Siir ❤

  • @bhatmajeed520
    @bhatmajeed520 6 лет назад

    thayynk uuuuuuuuuu sooooooo much sir.....

  • @vincentchu7700
    @vincentchu7700 2 года назад +1

    Sigma Mindset

  • @shawnh.3315
    @shawnh.3315 3 года назад

    Thank you Khan!

  • @Pa1_Thakur
    @Pa1_Thakur 3 года назад +3

    Is there any way to increment "i" by any number other than 1 ? (Using Sigma Notation)

    • @phoenixroyale
      @phoenixroyale Год назад

      Well, you could do a sigma notation where index i = 1, going to 10, and writing "2i" after the sigma symbol. That would add up all of the even numbers of 1 - 10.

    • @isavenewspapers8890
      @isavenewspapers8890 6 месяцев назад +1

      In the most basic form of sigma notation, the index only goes up in increments of 1. However, you can achieve the sum you want by simply rewriting the expression. For example, say you have the sum from i=1 to 5 of i, like so:
      1 + 2 + 3 + 4 + 5
      But say you want increments of 2 instead:
      1 + 3 + 5 + 7 + 9
      You can do this by writing it as follows: the sum from i=1 to 5 of 2i-1. The "2" coefficient in front of the i is to ensure that our terms go up in increments of 2, and we subtract 1 to make sure that our first term stays the same, just like we wanted.
      If you truly want the index itself to go up by anything other than 1, it is possible. You start by defining a set, such as S = {1, 3, 5, 7, 9}. After that, you can declare that i ∈ S, meaning "i is an element of S". Then, the sum of all i, with the condition that i ∈ S (which we put under the sigma), is 1 + 3 + 5 + 7 + 9.

    • @isavenewspapers8890
      @isavenewspapers8890 6 месяцев назад

      ⁠@@phoenixroyaleYou mean the even numbers from 2 to 20.

    • @Pa1_Thakur
      @Pa1_Thakur 6 месяцев назад

      @@isavenewspapers8890 thank you, 3 yrs lol

    • @isavenewspapers8890
      @isavenewspapers8890 6 месяцев назад

      @@Pa1_Thakur You're welcome.

  • @kritikakumeri5962
    @kritikakumeri5962 3 года назад

    Best explanation ... Thanku sir 😀

  • @minegun3096
    @minegun3096 10 месяцев назад

    I could meditate to this

  • @0xN1nja
    @0xN1nja 2 года назад

    it's called "for loop" in programming.

  • @ebenkaale8768
    @ebenkaale8768 5 лет назад +2

    were you not supposed to end at 49 as 50 is the position of the last number and you started with 0?

    • @joshmora3297
      @joshmora3297 5 лет назад

      eben kaale the goal is to reach that increment in the index, not create an index based on that value.

  • @MrDumndum
    @MrDumndum 7 лет назад +2

    How do you know what increment it is increased by? Is it always the value given by the index?

    • @LetTheWritersWrite
      @LetTheWritersWrite 7 лет назад +1

      the formula tells you that. The index might not even be the value of i. It could be the index i of X and you have a list of arbitrary numbers out of order. So something like a list 5,17,3,and 20 the value of X at index i will refer to one of those numbers in the list. i = 2 is the value X= 17 in this case. There could be a formula that says, go up the index i in twos or threes, or whatever.

    • @rlibby404
      @rlibby404 7 лет назад +2

      Yes, the index counts by ones from lowest to highest unless otherwise specified. The idea is that even if you want to count by tenths or tens, you would achieve that in the function by either dividing i by 10 or multiplying by 10. I suppose that constructing your own summations will be rare until college but by the time you need to construct them, you will want very badly to know how they work. Which is why I like your question. And why I'm here. Not really what I was looking for haha but I do like Sal's presentation and patience. Many college professors just ramble.

  • @user-mp7fx1ry2v
    @user-mp7fx1ry2v 5 лет назад

    Basically factorial but addition

  • @dev-ok1li
    @dev-ok1li 6 лет назад +18

    I rather pay u than my bloody tuition😂

  • @chenqiwen5005
    @chenqiwen5005 Год назад +2

    🤨🙂👉

  • @khuramkhalid5396
    @khuramkhalid5396 Год назад

    Thank you!

  • @Xnoob545
    @Xnoob545 3 года назад +1

    2:00 ok
    So lets use n
    100
    Σ n
    n = 1
    Like this right

  • @wolfiegames1572
    @wolfiegames1572 Год назад +1

    For loop moment

  • @milyas8743
    @milyas8743 3 года назад

    thanks

  • @Zak-ob5ze
    @Zak-ob5ze 5 лет назад +1

    How do you do it if you don't want to increase by 1

  • @hizkiahandoyo5941
    @hizkiahandoyo5941 8 лет назад

    thx alot it helps me actually I'm grade 7 but I skip grade

  • @smileys8745
    @smileys8745 3 года назад

    This man don't Forcha

  • @rogerdetuero5381
    @rogerdetuero5381 11 месяцев назад +1

    I somehow made it into the second year of a computer science-engineering degree without knowing this

  • @shashank...853
    @shashank...853 2 года назад

    Thank u sir ☺️

  • @owaisfoodpoint5800
    @owaisfoodpoint5800 4 года назад

    Nice method

  • @TheAmazingJon
    @TheAmazingJon 5 лет назад

    Was wondering how th this worked after getting out of work.

  • @aminator5929
    @aminator5929 3 года назад

    does it mean the first sequence starts like: (1+1)+(1+2)+(1+3)+(1+4)+(1+5)... instead of starting by 1?

  • @zuhaibasad7397
    @zuhaibasad7397 6 лет назад

    can the index be in decimals?

  • @paradox6647
    @paradox6647 3 года назад

    I am one giant enigma!

  • @kittjyess579
    @kittjyess579 7 лет назад +76

    God he has the sexiest voice!

  • @amanchopra
    @amanchopra 5 лет назад

    Do you know Salaman Khan is founder of Khan academy Thanks so much sir....

  • @sfaaa7A
    @sfaaa7A 9 лет назад

    this is really basic information, it's to late cause my exam is tomorrow.
    thanks anyway Sal !

    • @LearnMathsFree
      @LearnMathsFree 9 лет назад

      +The Chosen One How did the exam go?

    • @sfaaa7A
      @sfaaa7A 9 лет назад +2

      +Learn Maths Free i passed it with B grade :)

    • @adrians.v.s.k2777
      @adrians.v.s.k2777 8 лет назад +1

      +The Chosen One
      good job even though it's not A but it's still good good work buddy :-)

  • @nasound42
    @nasound42 6 лет назад

    thank you

  • @liviu201
    @liviu201 10 лет назад

    What is sum when k takes values from 1 to n, of K! * K ?

  • @virtuallyvortex
    @virtuallyvortex 8 месяцев назад +1

    Sigma. reminds me of something

  • @min11benja
    @min11benja 8 лет назад

    Thank you, this really helped me get a good sense of the sigma notation for sums.

  • @cringy7-year-old5
    @cringy7-year-old5 5 лет назад

    Just do this (x+1)x/2 it works sometimes.

    • @keyboardmannow
      @keyboardmannow 5 лет назад

      Cringy 7-Year-Old that only works for a natural number sequence lol

    • @cringy7-year-old5
      @cringy7-year-old5 5 лет назад

      keyboardmannow, “It only works *S O M E T I M E S .* “

    • @keyboardmannow
      @keyboardmannow 5 лет назад

      Cringy 7-Year-Old i acknowledge that, I was just stating that for other people who look

  • @joeyhockey4623
    @joeyhockey4623 2 года назад

    Wow this was absolutely awfully explained thanks! Way to go from using 1 and making it very simple to using pie and I squared. Definitely a genius way to confuse everyone!

  • @pawelpow
    @pawelpow 2 года назад

    It’s a for-in loop 😀

  • @Toandecuc
    @Toandecuc 10 лет назад +2

    hello i am from VN and i'm learning math in english and i have sth to ask
    How to read the notation of Sigma

    • @isavenewspapers8890
      @isavenewspapers8890 4 месяца назад

      "sum from [index] equals [bottom number] to [top number] of [expression being summed]"