Alternating Series, Types of Convergence, and the Ratio Test

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  • เผยแพร่เมื่อ 4 ก.พ. 2025

ความคิดเห็น • 54

  • @c001pers0n
    @c001pers0n 4 ปีที่แล้ว +100

    Kinda funny how you explain concepts better in 12 minutes than multiple hours of lecture from my professor.

    • @carmenouzon6690
      @carmenouzon6690 9 หลายเดือนก่อน

      Actually crazy

    • @carmenouzon6690
      @carmenouzon6690 9 หลายเดือนก่อน

      @@banaanpropaan9344there are proofs on here that are explained in 10 minutes and better than 2 hour explanations

  • @rirhassan6355
    @rirhassan6355 3 ปีที่แล้ว +7

    just to let u know ..u explain much better than my uni professor ....u r so good .........i understood all of it in 12 mins.......

  • @brysonmutinda5280
    @brysonmutinda5280 2 ปีที่แล้ว +15

    Simply the BEST proffesor,you make difficult things simple

    • @random6033
      @random6033 หลายเดือนก่อน

      or maybe others make simple things difficult

  • @hugoteupel8382
    @hugoteupel8382 11 หลายเดือนก่อน +2

    I’m writing math and physics exams this semester and I can say it’s all self-taught thanks to you😂much love

  • @risinglabyrinth5977
    @risinglabyrinth5977 11 หลายเดือนก่อน +1

    You scared me on question four of the comprehension test, you had me thinking I was supposed to tetrate XD! Thanks for these videos Professor Dave, these actually really help and give some intuition on these topics.

  • @gokuldath6084
    @gokuldath6084 5 ปีที่แล้ว +12

    You're the best in the business, thank you

  • @ahmadsab_
    @ahmadsab_ 23 วันที่ผ่านมา

    my professor refuses to give me the references for what we're studying, this video made me explain what i missed in the 4 lectures i was sick and couldnt attend, thanks Dave!

  • @rolofiend
    @rolofiend 5 ปีที่แล้ว +4

    You're actually a savior. Holy moly.

  • @sameersaifi3300
    @sameersaifi3300 3 หลายเดือนก่อน +2

    I Am from India🇮🇳 I totally understand the topic

  • @samirouhani
    @samirouhani 8 หลายเดือนก่อน +1

    Thanks a lot. Just one point, from what I've been studying, I've learned that the AST only tells us whether an alternating series is convergent or not, and it doesn't tell us anything about its divergence.

  • @allo9228
    @allo9228 6 ปีที่แล้ว +12

    Hope you're doing well Professor ☺️

  • @choo1030
    @choo1030 4 ปีที่แล้ว +8

    I honestly can't believe I've purchased a $150 textbook for contents that could be boiled down in 2 days worth of lecture videos. I'm not saying textbook is useless. But textbook has its limit as it cannot show the reader animations of how some things are done.
    Textbook is really only needed for practice problems.

  • @roronoazoro6153
    @roronoazoro6153 3 ปีที่แล้ว +6

    At the example at 4:38 the number 1/5 = 0.2 and 4/12 = 0.3 which is larger. The terms don't get smaller. How can this series converge?

    • @thesakinator7639
      @thesakinator7639 3 ปีที่แล้ว +1

      thats why its called conditionally convergent, because its convergency hinges on the fact that the terms ascilate from positive to negative so the sum does in fact get smaller and smaller

    • @DarinBrownSJDCMath
      @DarinBrownSJDCMath 2 ปีที่แล้ว +3

      Because any finite number of terms don't affect convergence, all that is required is that the terms are *eventually* decreasing, i.e. b_(n+1) = k for some k. This is something that happens a lot of the time, and it was glossed over in the video. You can check the terms are eventually decreasing by showing the derivative of x^2/(x^3 + 4) is eventually negative.

  • @Kiky_MedPhysicist
    @Kiky_MedPhysicist 5 หลายเดือนก่อน

    Thank you sir for your dedication! 🙏

  • @unknownbeing8222
    @unknownbeing8222 4 ปีที่แล้ว +12

    Im now studying mathematics lol, i never thought i would do this.

    • @demonnogo
      @demonnogo 3 ปีที่แล้ว +4

      Same, lol! I literally have no need or reason to but it's something that I feel compelled to do.

    • @ian.ambrose
      @ian.ambrose 2 ปีที่แล้ว +1

      @@demonnogo You study math just because you feel like so? Woah this stuff you are studying is hard. Knowing that people study math for fun is scary.

    • @klasta2167
      @klasta2167 ปีที่แล้ว

      @@ian.ambrose Im studying for fun too, im 16 lol 💀

  • @ivowehsely9131
    @ivowehsely9131 ปีที่แล้ว

    I love you professor Dave!

  • @gp2580
    @gp2580 6 ปีที่แล้ว +1

    Very interesting - always enjoy your videos - thank you

  • @محمودحقياسماعيلرشيد
    @محمودحقياسماعيلرشيد 3 ปีที่แล้ว +5

    the minute 4:40 it is not 16/70 it is 16/68

  • @NeymarJR-du9rb
    @NeymarJR-du9rb 6 ปีที่แล้ว +1

    Thank you

  • @zhoud2005
    @zhoud2005 4 ปีที่แล้ว

    Great lectures, really enjoyed them. thanks

  • @ian.ambrose
    @ian.ambrose 2 ปีที่แล้ว

    Thank you Professor.

  • @bapisaha1766
    @bapisaha1766 6 ปีที่แล้ว +1

    Thank you professor

  • @omerelhagahmed551
    @omerelhagahmed551 หลายเดือนก่อน

    I think it's a typo at 2:25 it's "

  • @newtoniangaming4832
    @newtoniangaming4832 3 ปีที่แล้ว +3

    10:51 but if we just apply
    limit n tends to infinity to (1+1/n)^n we get
    = (1 + 1/infinity)^infinity
    = (1+0)^infinity
    = 1
    so test must be inconclusive rather than divergent right?
    Please correct me if I am wrong.

    • @kjl3080
      @kjl3080 3 ปีที่แล้ว

      One word:
      E

    • @DarinBrownSJDCMath
      @DarinBrownSJDCMath 2 ปีที่แล้ว +1

      This is why it's terrible when teaching limits to students just learning, to do things like "plugging in infinity", as around the 5:00 mark. This kind of sloppy calculation is okay if you're experienced with limits and indeterminate forms, but it often leads students to wrong conclusions as you've done here. To answer your question, 1^(infinity) is an indeterminate form, and we cannot conclude any value for the limit. (1 + 1/n)^n does converge to e.

    • @kpkrkr4038
      @kpkrkr4038 ปีที่แล้ว

      Same answer I get

  • @subforsubcommunitycenter6961
    @subforsubcommunitycenter6961 5 ปีที่แล้ว +2

    Please add all the details about limits

    • @ProfessorDaveExplains
      @ProfessorDaveExplains  5 ปีที่แล้ว +3

      that's in another video earlier in the calculus playlist

    • @NewWesternFront
      @NewWesternFront ปีที่แล้ว

      @@ProfessorDaveExplains sir please but what is 2+2 and how to prove it sir please sir

  • @honeydevaang732
    @honeydevaang732 2 ปีที่แล้ว +1

    so as i understand, the alternative series and all the series associated with the calculus, we only need to find if they are convergent or divergent. but why do we have to do so? what is the relevance of convergence and divergence? maybe it could sound silly but this is my first interaction with the calculus so please pardon me for that.

    • @NewWesternFront
      @NewWesternFront ปีที่แล้ว

      good question. I looked it up and the main answer i found was basically "to help you with even higher level math." whelp.

  • @ramiltaghiyev9712
    @ramiltaghiyev9712 ปีที่แล้ว

    7:53 guys, why is the series on the right divergent? I heard about the p-series

    • @aliffhaikal9256
      @aliffhaikal9256 9 วันที่ผ่านมา

      Ya it should be harmonic series

  • @Nemoguzapomnit
    @Nemoguzapomnit 6 ปีที่แล้ว +3

    Thx a lot fot that video! About problems at the end of the video: Σ[(-2)^n/3^n] is it relevant just to rewrite it as Σ[(-2/3)^n] and say that: as r=-2/3 and its less then 1, then the serires is converges?

    • @ravitheja012345
      @ravitheja012345 6 ปีที่แล้ว +2

      r=-2/3 and |r|=2/3

    • @carultch
      @carultch 3 ปีที่แล้ว

      How do you pronounce the difference among "p", "п", and "π", when discussing mathematics in your language?

    • @Nemoguzapomnit
      @Nemoguzapomnit 3 ปีที่แล้ว

      @@carultch we don't use russian letters in math. But anyway "п" sounds like "pæ". And about "p" and "π" - in case with "p" we would say "p variable"

    • @carultch
      @carultch 3 ปีที่แล้ว

      @@Nemoguzapomnit Ok, that makes sense.
      Greek speakers dislike the fact that English speakers shift the vowel when referring to π, so that it sounds like pie. But we have to do that, otherwise both p and π would sound identical, like the word "pea". I found out that they say their own π to sound like like pea, and the Latin p like "pay", as it is most commonly named in languages that use Latin letters.
      I asked you, because I thought a similar issue might persist in your language, except with three different versions of the letter with very similar names.

    • @Nemoguzapomnit
      @Nemoguzapomnit 3 ปีที่แล้ว

      @@carultch it could be but we mostly never use "p" variables

  • @sciencedude2355
    @sciencedude2355 3 หลายเดือนก่อน

    how does the sum of (-1)^(n-1)/n converge if the sum of 1/n diverges?

  • @elanaweiss1120
    @elanaweiss1120 2 หลายเดือนก่อน

    why does it in the ratio test approach e

  • @yourfutureself4327
    @yourfutureself4327 ปีที่แล้ว +1

    💚

  • @kpkrkr4038
    @kpkrkr4038 ปีที่แล้ว

    What is the use of series?

    • @xarlition
      @xarlition 10 หลายเดือนก่อน

      the simplest example is drug dosage calcs

  • @Dkdkxncnchz
    @Dkdkxncnchz 3 ปีที่แล้ว

    best