10 Series That You Can Do In Your Head (secret weapon: The List)

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  • เผยแพร่เมื่อ 19 ธ.ค. 2024

ความคิดเห็น • 162

  • @Л.С.Мото
    @Л.С.Мото 5 ปีที่แล้ว +144

    Ln(1) = 0 and since its in the denominator, you would be end up in math jail again.

    • @Otomega1
      @Otomega1 5 ปีที่แล้ว +17

      n=2 :D

    • @BlondThunder
      @BlondThunder 5 ปีที่แล้ว +7

      Look again, n=2 and not 1

    • @Л.С.Мото
      @Л.С.Мото 5 ปีที่แล้ว +27

      Yeah, but he asked why he didn't go below 2 to start his journey into infinity

    • @rodrigothomaz6329
      @rodrigothomaz6329 5 ปีที่แล้ว

      @@Otomega1 Guys, look at the (ln n)/n series. The guy is right, he deserves the jail

    • @Otomega1
      @Otomega1 5 ปีที่แล้ว +2

      @@rodrigothomaz6329 What's the problem with this series?

  • @Lordoftheflies234
    @Lordoftheflies234 5 ปีที่แล้ว +78

    I'm going to teach Calc II for the first time this summer, I'm here to refresh my memory and to find good tips and tricks to give my students.

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว +19

      Very nice!
      I am teaching calc 2 again over the summer. How many weeks do you have for your class?

    • @Lordoftheflies234
      @Lordoftheflies234 5 ปีที่แล้ว +14

      @@blackpenredpen 4 weeks. It's going to be fast!

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว +15

      Lordoftheflies234 what?!!!!!!! 4 weeks?!!!! Mine is 5 and I think it’s crazy enough. May I ask what school?

    • @Lordoftheflies234
      @Lordoftheflies234 5 ปีที่แล้ว +13

      @@blackpenredpen A cegep (college) in Quebec city. I'd like to have 5 weeks too!

    • @Sasori_322
      @Sasori_322 5 ปีที่แล้ว +12

      Good luck sir

  • @alwysrite
    @alwysrite 5 ปีที่แล้ว +37

    I like how you use "everybody" instead of "everything" -- brings the things to life and gives them personality !

  • @zuccx99
    @zuccx99 5 ปีที่แล้ว +69

    Tomorrow our professor is giving us a blitz test on series calc 2.
    I think you have just saved me.

  • @Supernova799
    @Supernova799 5 ปีที่แล้ว +47

    That secret weapon used during the competitive exam

  • @lalgerielibre9519
    @lalgerielibre9519 2 ปีที่แล้ว +1

    Best Video about this title so far 🤝🤝♥️♥️♥️

  • @oscartroncoso2585
    @oscartroncoso2585 5 ปีที่แล้ว +13

    7:30-7:37 best part

  • @Dalton1294
    @Dalton1294 4 ปีที่แล้ว +2

    The reason why the summation of 1/(0.8)^n as n goes from 1 to infinity is because the common ratio is greater than 1. In order for a infinite geometric series to converge, r

  • @drpeyam
    @drpeyam 5 ปีที่แล้ว +11

    10/10 would watch again!

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว +4

      Dr Peyam definitely! Final in 10 days!!

  • @jhonandrew6973
    @jhonandrew6973 5 ปีที่แล้ว +18

    My precious secret: The telescoping series.

  • @kevinbueno5175
    @kevinbueno5175 5 ปีที่แล้ว +4

    That list is sooo helpful!! Im studying independently to prepare for school and my biggest problem was Series. That list helps so much when I use the Comparison Test!!! Thank you soo much!!

  • @saddiqjeelani563
    @saddiqjeelani563 5 ปีที่แล้ว +8

    I finished this class and still come back to these videos time and again just because he's so enjoyable to watch. This guy is truly phenomenal, explaining the toughest concepts like they're child's play. One in a million. Props.

  • @ianmi4i727
    @ianmi4i727 2 ปีที่แล้ว

    Something similar can be done with some limits and improper integrals. Examples:
    Limits: lim (x->+ or -infinity) 2x/sqrt(x^2-3) [considering asymptotic behavior of square root], lim (x->+ or -infinity) (x^2+3x+1)/sqrt(4x^2+x^3-2x^2) [same], lim (x->infinity) (1+5x/(2x^2-x+2))^(6x-7) [there's a tricky shortcut for this one]
    Improper integrals: int (from 3 to infinity) (x^3+2)/sqrt(x^8+1) [asymptotic behavior of square root or comparison test], int (from 3 to infinity) exp(3x)/(exp(6x)+5exp(3x)+2) [asymptotic behavior of the sum or comparison test]; hints: (i) int (from a to infinity) exp(-px) converges if p>0, diverges if p1, diverges if p

  • @arcaninejoe4574
    @arcaninejoe4574 5 ปีที่แล้ว +2

    1/(0.8)^n diverges because it is a geometric series with a common ratio of 10/8 which is greater than 1.

  • @Engineering_conceptsUOM
    @Engineering_conceptsUOM 3 ปีที่แล้ว +1

    Thank you sir

  • @pierreabbat6157
    @pierreabbat6157 5 ปีที่แล้ว +11

    I thought you wanted us to compute the sums. Some sums I can do in my head, but two of them (one of which diverges) are values of the zeta function at non-integral arguments, which I don't know.

  • @ShorTBreak167
    @ShorTBreak167 5 ปีที่แล้ว +20

    It start at 2 because ln1 = 0
    So if we start at n=1 we start with 1/0 which is undifine

  • @ffggddss
    @ffggddss 5 ปีที่แล้ว +2

    Very nice!
    For (F), I would just use the comparison test against the harmonic series, but shifted by one term:
    1/√(n²+1) > 1/(n+1), for n ≥ 1
    But ∑₁ºº 1/(n+1) = ∑₂ºº 1/n diverges , therefore, (F) diverges.
    Fred

  • @dario2886
    @dario2886 5 ปีที่แล้ว +8

    4:34 you can feel how badly he wanted to say to what special value it converges...

  • @alexdemoura9972
    @alexdemoura9972 5 ปีที่แล้ว

    The List:
    alternatively we could insert the n^1 or n and assume in the next term of inequality as p>1. In this way:
    Ln(n)

    • @alexdemoura9972
      @alexdemoura9972 5 ปีที่แล้ว

      Silly poem to memorize the List and divergence/convergence of inverses:
      Love is power.
      Power is a fact!
      Less is power itself.
      The inverse until this,
      Greater power to itself comes.
      Just replace "is" or "itself" by the favorite variable n or x.

    • @alexdemoura9972
      @alexdemoura9972 5 ปีที่แล้ว

      Got it! I never got structured text in YT before, not even in Chrome, but for some reason I got it in my Android phone, I used WhatsApp as Draft notepad, copy and paste.

  • @BrainGainzOfficial
    @BrainGainzOfficial 5 ปีที่แล้ว +3

    Great video! Always nice to have a cal 2 refresher :)

  • @andreapaps
    @andreapaps 4 ปีที่แล้ว

    The list... So brilliant to summerise convergent and divergent series in a single line :D Also you explained it like a baws.

  • @bmdiscover7827
    @bmdiscover7827 2 ปีที่แล้ว +1

    The List proof plz , and why 1/n is the border btwn convergence and divergence. with thanks

  • @VibingMath
    @VibingMath 5 ปีที่แล้ว +1

    Mnemonic:
    L for ln
    P for n^p
    B for b^n
    F for factorial
    N for n^n
    L P B F N
    (um......I dont want to think of some dirty words)

  • @priyanksisodia5889
    @priyanksisodia5889 5 ปีที่แล้ว +2

    thank u sir, for this, this is helpful to me

  • @ethanbartiromo2888
    @ethanbartiromo2888 5 ปีที่แล้ว +1

    This was an amazing video!

  • @bhuvird178
    @bhuvird178 5 ปีที่แล้ว +1

    Thank u dear this will help me in teaching children. I going to teach children in 23 may. Thank u

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว

      Who are the children?

    • @bhuvird178
      @bhuvird178 5 ปีที่แล้ว

      @@blackpenredpen 6 to 12 students dear

  • @redrosin99
    @redrosin99 5 หลายเดือนก่อน

    A) e-1
    B) diverges
    C) n/(n-1)
    D) 0.5
    E) diverges
    F) diverges
    G) converges to?
    H) diverges
    I) diverges
    J) diverges (stirling)

  • @hassanalihusseini1717
    @hassanalihusseini1717 5 ปีที่แล้ว +2

    Nice video! Can you make a video about the Kempner serieses? I was always fascinated b them how they can converge when the harmonic series and the series over all prime numbers diverges?

  • @fragaleenzo
    @fragaleenzo 5 ปีที่แล้ว +1

    I don't understand at 8:30 (F). Since √(n²+1) > √(n²) it implies that 1/√(n²+1) < 1/√(n²) which means the series is slightly below the critical value i.e. converges no?

    • @shlomozerbib388
      @shlomozerbib388 5 ปีที่แล้ว +1

      I had the same remark. But you are the first to ask ;)

    • @matrefeytontias
      @matrefeytontias 5 ปีที่แล้ว +1

      To understand that, take the behaviour at infinity. As n goes very big, it becomes so much bigger than the 1 that you add to it that it begins to not matter whether you add a 1 or not. So eventually "at infinity", n^2 + 1 ≈ n^2, and so 1/sqrt(n^2 + 1) ≈ 1/sqrt(n^2) = 1/n, the sum of which diverges.
      But then you could argue "yes but I have to go to a very big n before the 1 starts to not matter !". The key of that answer is in the fact that the harmonic series diverges : the sum of 1/n goes to infinity regardless of the starting n ; whether you start summing at n = 1, n = 10^68 or whatever else, it will never converge and continue increasing to infinity. Then, you could say that you sum starting at some n0 that is big enough that for every n > n0, n^2 + 1 ≈ n^2. This way, the sum of 1/sqrt(n^2 + 1) starting from n = n0 to ∞ will be roughly equal to the sum of the harmonic series starting from n0, which still diverges. Since you would only be adding positive numbers by adding the terms from 0 to n0 that you didn't sum, the complete series diverges. QED
      I tried to keep it simple, but if there's something you didn't understand, feel free to ask. Also if you want to look at the proper, rigorous way to do that, it's called "equivalent series". We say that two series (u_n) and (v_n) are equivalent if their ratio tends to some constant value, ie lim u_n/v_n = C some non-zero constant value. The big takeaway is that if sum(u_n) converges and (u_n) and (v_n) are equivalent series, then sum(v_n) converges too. The contraposition says that if (u_n) diverges and (u_n) and (v_n) are equivalent series, then sum(v_n) diverges too. It's pretty hard to prove actually, and uses epsilon-delta methods IIRC

    • @shlomozerbib388
      @shlomozerbib388 5 ปีที่แล้ว

      @@matrefeytontias ok understood ty

    • @lukashorak9639
      @lukashorak9639 5 ปีที่แล้ว

      @@shlomozerbib388 Something to think about: there are infinitely many sequencies a_n such that n< a_n< n^(1+a) for any a>0. For example n*ln(n), n*ln(n)*ln(ln(n)) etc. So if a_n is slightly larger than n, you dont automatically get convergence for the a_n series. The a_n sequence must be larger enough to be equivalent to n^(1+a).

    • @dalek1099
      @dalek1099 2 ปีที่แล้ว

      You can use n^2>=1 and thus n^2+1=1/sqrt(n^2+n^2)=1/sqrt(2n^2)=1/sqrt(2)1/n which diverges because 1/n diverges.

  • @italixgaming915
    @italixgaming915 3 ปีที่แล้ว

    Even if you only want to know if the series diverges or converges, you can recognise some of them directly and not only say that they converge but show their limit. We know for example that for any real number x we have: exp(x)=sum(n=1,inf.,x^n/n!). So we know that the first series converges to exp(1)=e.

    • @BaterWottleDog
      @BaterWottleDog ปีที่แล้ว

      it should be sum n=0 not n=1 for it to equal e so that series actually converges to e-1 not e

  • @UtkarshKSahu
    @UtkarshKSahu 5 ปีที่แล้ว +3

    Thanks Sir it will definitely help me in my jee advanced preparation 💕💕

    • @YASH-jz4sh
      @YASH-jz4sh 5 ปีที่แล้ว

      Tujh se nhi ho payega chod de kuch nhi ho payega tujh se

    • @YASH-jz4sh
      @YASH-jz4sh 5 ปีที่แล้ว

      Ma baap ka paisa mat kharab kar

  • @roddeguzman9958
    @roddeguzman9958 5 ปีที่แล้ว

    If there was an esport for math you would be a top player. Bless you master pen

  • @diaconescutiberiu7535
    @diaconescutiberiu7535 5 ปีที่แล้ว

    Question: For n>1 ln n is >0. In fact (in general) for n in (1, e) we have ln n in (0, 1)....so how can we say for any n ln n > 1? It is not true...but... for n>e we get ln n > 1!!!

  • @pratyasheeojah6311
    @pratyasheeojah6311 5 ปีที่แล้ว +1

    Thank you

  • @LucasEccard
    @LucasEccard 5 ปีที่แล้ว +8

    Why don't you make a video trying to find out the value of some convergent series. Like letter A that is e-1 by the expansion of taylor series

  • @connerp6878
    @connerp6878 5 ปีที่แล้ว

    Hey I have a fun calc 1 problem I’d like u to try!
    The curve y = ax^2 + bx +c passes though the point (1,2) and is tangent to the line y=x at the origin. Find a, b, c.

  • @adityamajhi5608
    @adityamajhi5608 5 ปีที่แล้ว +2

    love this

  • @mattezmatrick9429
    @mattezmatrick9429 5 ปีที่แล้ว

    Yay good list i love it :) my maths tacher gave the same trick! Still happy to have you as a complement :)

  • @shawaizhaider3978
    @shawaizhaider3978 ปีที่แล้ว +1

    Factorial ❌❌ Factorio✅✅

  • @lolidemon3163
    @lolidemon3163 4 ปีที่แล้ว

    1/((.8)^n) doesn't even approach zero since .8 to any power is a decimal and if u divide any number by a decimal it spits out a larger number so it diverges regardless

  • @Lamiranta
    @Lamiranta 5 ปีที่แล้ว +4

    Philosopher: bprp, can we get best friend?
    Bprp: no, we have best friend at home.
    Best friend at home: 100/(1-x)

  • @SuperV2g2to
    @SuperV2g2to 2 ปีที่แล้ว

    For those who don't understand why E) diverges:
    The serie is a Bertrand's serie, and we have a = 0 < 1 (from n^a) then it diverges.

  • @gamedepths4792
    @gamedepths4792 5 ปีที่แล้ว +5

    Can you provide the link to proofs of this list please?

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว +3

      I haven't done the whole proof yet but here's a small part: th-cam.com/video/ELRSCt66MQQ/w-d-xo.html

  • @wkstarscape293
    @wkstarscape293 5 ปีที่แล้ว

    Natural log of 1 is zero, the reciprocal of zero is undefined, so to make the infinite series meaningful, all the terms should be defined, which is why the index starts at two and not one

  • @SirPuFFaRiN
    @SirPuFFaRiN 5 ปีที่แล้ว +1

    In the description, the second is the series of 1/n^(2/3)

  • @Rain-ju2ge
    @Rain-ju2ge 7 หลายเดือนก่อน

    I like how my professors doesn't taught me this 🙃
    Thank you professor, you are very useful

  • @ariel_haymarket
    @ariel_haymarket 5 ปีที่แล้ว +2

    wouldn't 1/ln n lead to a problem with n = 1, since ln 1 = 0 and therefore would render the equation undefined?

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว +2

      That's why I started with n=2

    • @ariel_haymarket
      @ariel_haymarket 5 ปีที่แล้ว +1

      @@blackpenredpen I figured as much. Thanks for the challenge question.

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว

      @@ariel_haymarket yup!! : )))) Thanks for watching too!

  • @ayushdwivedi2039
    @ayushdwivedi2039 5 ปีที่แล้ว +6

    Please bro !!!! Do make next video on 100 DIFFERENTIAL EQUATIONS IN ONE TAKE!!! PLEASE🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻

  • @jacedonnelly712
    @jacedonnelly712 5 ปีที่แล้ว

    how would I solve integral of dx/(x^2+2x-3)^0.5

  • @Maharshi_Riemann_RC
    @Maharshi_Riemann_RC 5 ปีที่แล้ว +1

    Many of those given serie's nature cam be conclude by just using Cauchy Condensation

  • @euriskoo
    @euriskoo 5 ปีที่แล้ว

    You have a distance of 20 meters to the equal parts of each section is equal to x so that the first x---->t then the second x ----->1/2t then 1 / 4t … and so on, Calculate the total distance in terms of X, and the time took?

  • @UniformDelta00
    @UniformDelta00 5 ปีที่แล้ว +5

    #DIV/0! ln(1)

  • @ketos2ketos259
    @ketos2ketos259 5 ปีที่แล้ว +1

    Bravo :-)

  • @qingyangzhang887
    @qingyangzhang887 5 ปีที่แล้ว

    Well 7:10, n cannot be 1 because ln(1) = 0, so you would get 1/0, which is undefined.

  • @semiconductorsinarabic4090
    @semiconductorsinarabic4090 5 ปีที่แล้ว

    incredible, thanks. plz tell me why your microphone is this big(i feel sorry for hands carrying it ). :p

  • @bucketsniper5488
    @bucketsniper5488 4 ปีที่แล้ว

    Is it true that you do not use the comparison test here?

  • @bca6943
    @bca6943 5 ปีที่แล้ว +3

    If you take n from 1, then the lnn would be 0
    1/0 is undefined

  • @chouayabdelali3241
    @chouayabdelali3241 5 ปีที่แล้ว +1

    do more algebra things :) pls

  • @boriswolfsoul6629
    @boriswolfsoul6629 5 ปีที่แล้ว

    Excuse me, I didn't undertand the F. The aproximation is right, and for larger numbers sum 1/sqrt(n^2+c) aproximate sum 1/sqrt(n^2) = 1/n, when n go to infinity (with c any constant). But sum 1/n^p diverge only when p is bigger or equal to 1. Until this point, we agree.
    But 1/sqrt(n^2+c) is ALWAYS lower than 1/n, although slightly. So, what happens?

    • @dalek1099
      @dalek1099 2 ปีที่แล้ว

      You can use n^2>=1 and thus n^2+1=1/sqrt(n^2+n^2)=1/sqrt(2n^2)=1/sqrt(2)1/n which diverges because 1/n diverges.

  • @joepvoorburg6539
    @joepvoorburg6539 5 ปีที่แล้ว +2

    E can't be the sum from 1 to infinity, because ln(1)=0 so you would have 1/0 which doesn't exist.

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว

      Yup!

    • @joepvoorburg6539
      @joepvoorburg6539 5 ปีที่แล้ว

      @@blackpenredpen Hey, I just wanted to say that your videos got me really interested in math. I'm even gonna study it next year. Thank you so much.

  • @kee40040310
    @kee40040310 5 ปีที่แล้ว

    好棒的list!!

  • @mehmeteminconkar2590
    @mehmeteminconkar2590 ปีที่แล้ว

    N equals one gives us zero on the denominator which is undefined

  • @killing_gaming0973
    @killing_gaming0973 ปีที่แล้ว

    ln 0 is infinity, ln 1 is zero. 0+ infinite cannot be defined. That's why it starts from 2

  • @abrown6539
    @abrown6539 5 ปีที่แล้ว

    I have a problem with equation F. The denominator (n^2+1)^0.5 gets arbitrarily close to n as n goes to infinity, fine. Since the harmonic series is divergent, this must be divergent, right? But wait. That denominator is ALWAYS infinitesimally MORE than n. So what we have is a series that consists of terms that are of the form 1/n^p, where p MUST be greater than one every time. Does that not suggest this series is convergent? In other words, the harmonic series is the hard boundary of divergence, and this equation is on the convergent side of it, even if only infinitesimally. No?

    • @abrown6539
      @abrown6539 5 ปีที่แล้ว

      Also, the explanation for I doesn't make sense in light of the explanation for J. In I, ln(n) is much smaller than n^1 as n goes to infinity, so the limit should go to zero and the series converge. It's the same reasoning used in J. What's the difference?

    • @dalek1099
      @dalek1099 2 ปีที่แล้ว

      The limit going to 0 isn't enough for convergence.

    • @dalek1099
      @dalek1099 2 ปีที่แล้ว

      You can use n^2>=1 and thus n^2+1=1/sqrt(n^2+n^2)=1/sqrt(2n^2)=1/sqrt(2)1/n which diverges because 1/n diverges.

  • @pooi-hoongchan8680
    @pooi-hoongchan8680 5 ปีที่แล้ว +2

    Sorry, you did say n approaches infinity. Forgive this old man.

  • @wojciechchudek9379
    @wojciechchudek9379 4 ปีที่แล้ว

    I wait for formul for every sume.

  • @DruishQueen
    @DruishQueen 5 ปีที่แล้ว

    Wait why does H diverge..according to the list, isn't it bigger than others that converge so it also must converge?

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว +1

      1/0.8 = 5/4 and by geometric series. It diverges.

  • @einnorw
    @einnorw 5 ปีที่แล้ว

    I'm so confused. This makes no sense to me. So because it's less on the list it's convergent?

  • @Learnerz_isle
    @Learnerz_isle 5 ปีที่แล้ว

    Lim n^n=1 as n ->infinity

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว

      Aroonima Sahoo
      I think you are thinking about the nth root of n

  • @chinesecabbagefarmer
    @chinesecabbagefarmer 5 ปีที่แล้ว

    nike! i wonder if they make brown jackets? 🤔

  • @visionaerie
    @visionaerie 4 ปีที่แล้ว

    can somebody PLEASE tell me what "The List" is???

  • @jomelherras8910
    @jomelherras8910 5 ปีที่แล้ว

    I love you😍

  • @nimmira
    @nimmira 5 ปีที่แล้ว

    in-fi-nit-lee :)

  • @WildNtrOut
    @WildNtrOut 5 ปีที่แล้ว

    So im guessing this is how our final will be :)?

  • @AJ420BLAZIN
    @AJ420BLAZIN 2 ปีที่แล้ว

    ln(1)=0 and it’s in the denominator and we cannot divide by 0

  • @anshul4589
    @anshul4589 5 ปีที่แล้ว +1

    Can you please make video tutorial on series convergence and divergence.
    I am so confused.

  • @alitarek7164
    @alitarek7164 5 ปีที่แล้ว +1

    I want to learn about the list
    And diverge and converge
    I need a link pls

  • @zanti4132
    @zanti4132 4 ปีที่แล้ว

    All these summations are pretty non-controversial. My question is, is the following summation convergent or divergent (n goes from 1 to ∞)?
    ∑ 1/(n² - 10n + 24)

    • @italixgaming915
      @italixgaming915 3 ปีที่แล้ว

      When you look at n²-10n+24, you know that the product of the roots is 24 and that the sum is 10 so n²-10n+24=(n-4)(n-6). Which means that 1/(n²-10n+24) is not defined at all for n=4 or n=6. So the answer is not that the series converges or diverges, it doesn't even exist. We need to be able to calculate every term of a series.

    • @zanti4132
      @zanti4132 3 ปีที่แล้ว

      @@italixgaming915 It is certainly true that the n=4 and n=6 terms are undefined, but does that necessarily mean the summation doesn't exist? In fact, by using partial fractions we can rewrite the summation as (1/(x-6) - 1/(x-4))/10. Then, by expanding the terms, we get (1/10)(-1/5 - (-1/3) + (-1/4) - (-1/2) + (-1/3) - (-1/1) + ...) when everything cancels out except for two terms - including the two undefined values - giving us -9/200 for the sum.

    • @italixgaming915
      @italixgaming915 3 ปีที่แล้ว

      @@zanti4132 1/0 is undefined and 1/0-1/0 is still undefined.

    • @zanti4132
      @zanti4132 3 ปีที่แล้ว

      @@italixgaming915 It's debatable. To take a similar situation from calculus, is the integral of 1/x from -1 to +1 equal to zero, or is it undefined?

    • @italixgaming915
      @italixgaming915 3 ปีที่แล้ว

      @@zanti4132 Undefined. I suppose that you say that if you integer 1/x on [-1;-1/n] and [1/n,1] you obtain 0 so this is why you pretend that 0 could be the result but if you integer on [-1;-1/n] and [1/n²,1] you obtain log(1/n²)-log(1/n)=log(1/n) and you have an infinite limit when n ---> infinite.

  • @Brandon-yk6st
    @Brandon-yk6st 11 หลายเดือนก่อน

    1/(b)^n. b

  • @jinishtrivedi2429
    @jinishtrivedi2429 5 ปีที่แล้ว +4

    Please make a video on derivative of x^x by first principal because no body has done it by first principal
    Please like my comments if you also want it

  • @istvanszabo3275
    @istvanszabo3275 ปีที่แล้ว

    My teacher says there is no such thing as "The List" 😢 What is its official name or what theorem(s) is it based on?
    I keep failing saying The List 😢
    Thank you!

  • @abraham5781
    @abraham5781 4 ปีที่แล้ว

    Bold of you to assume that I am that smart......
    P.S you were wrong mate

  • @Czeckie
    @Czeckie 5 ปีที่แล้ว

    that explanation for F) feels incomplete and unsatisfying. The correct way is to derive the inequality 1/n

  • @flyingpenandpaper6119
    @flyingpenandpaper6119 3 ปีที่แล้ว

    Little bit of clickbait. The title seems to imply you can also evaluate the convergent series in your head. I was wondering how to do that for C. Of course you can't.

  • @gonzalofdez3711
    @gonzalofdez3711 5 ปีที่แล้ว

    divergess...

  • @紀昱安-t8j
    @紀昱安-t8j 5 ปีที่แล้ว

    0.16460844=(x^(x)*1.7^(1.7))/((x+1.7)^(x+1.7)) how to solve step by step?

  • @JorgeC.Ortiz.
    @JorgeC.Ortiz. 5 ปีที่แล้ว +1

    Late, two days late :(

  • @Brandon-yk6st
    @Brandon-yk6st 11 หลายเดือนก่อน

    1/0🚫

  • @Anonym-pv2nj
    @Anonym-pv2nj 5 ปีที่แล้ว +1

    we start with ln2 because ln1 is equal to zero and you can not devide by zero

  • @pooi-hoongchan8680
    @pooi-hoongchan8680 5 ปีที่แล้ว +1

    The list is not correct

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว

      Which part?

    • @pooi-hoongchan8680
      @pooi-hoongchan8680 5 ปีที่แล้ว +1

      Sorry, my maths is no good. I think you should specify n approaches infinity. Or you should say for large n. I was plugging in some figures but this did not work.
      I am a 70 yrs old guy learning a lot of maths from you. I did maths in Uni and 98 % percent forgotten.

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว +2

      @@pooi-hoongchan8680
      It's okay. No worry about it. I did mention about as n goes to inf right next to "the list".
      And wow I am glad to have you here. Hope you enjoy my channel so far! Thank you.

  • @samyakjain4468
    @samyakjain4468 5 ปีที่แล้ว

    😍😍😍😍

  • @مسيومدين-ط2م
    @مسيومدين-ط2م 5 ปีที่แล้ว

    I want to get citizenship or residency - how can you help me please

  • @oscartroncoso2585
    @oscartroncoso2585 5 ปีที่แล้ว +2

    FIRST