What series convergence test do I use?

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  • Опубліковано 19 січ 2025

КОМЕНТАРІ • 269

  • @blackpenredpen
    @blackpenredpen  9 місяців тому +9

    Get the file and the notes first 👉 www.patreon.com/posts/102348401

    • @FarukFahmi-h1k
      @FarukFahmi-h1k 8 місяців тому

      Sirr does it need for the note you posted a money

  • @smokebonde9943
    @smokebonde9943 3 роки тому +356

    The video thumbnail reminded me of Organic Chemistry Tutor

    • @Archius_09
      @Archius_09 3 роки тому +14

      at first I taught it was him but then I saw the thumbnail carefully and then channel name

    • @mikhaelhalbar417
      @mikhaelhalbar417 2 роки тому +20

      OCT is literally god

    • @夜神月-l8q
      @夜神月-l8q 2 роки тому

      Broo trueee

    • @Andalfulfulde
      @Andalfulfulde Рік тому +4

      ​@@Archius_09 that man has no mate😂😂. Five of his kind does not exist on school work.
      His last video made understood MOMENT OF INNERTIA that I have being struggling with since 2019😂😂😂😂.
      BlackPenRedpen, You are Legit with Math Also. But that father is un measurable 😢

    • @montagecrazy4u
      @montagecrazy4u Рік тому +2

      I got click baited😢

  • @TheMooseCaboose
    @TheMooseCaboose 3 роки тому +88

    I am going to tear up in happiness as I have never been good with condensing notes to make things less overwhelming. That notes PDF is a game-changer for me. Thank you so much BPRP. I am so happy to have been subscribed to you all these years as you motivated me to become a math tutor. My goal is to make it up to Calc II and this will give me indescribable amount of value!

    • @yodelersparadise
      @yodelersparadise 2 роки тому

      It looks interesting but I can't understand a word you say.

    • @ademansor3970
      @ademansor3970 9 місяців тому

      Can you share it with me please?

  • @treanungkurmal803
    @treanungkurmal803 4 роки тому +204

    Timestamp
    4:38 Question 1
    9:07 Question 2
    14:00 Question 3
    23:40 Question 4
    30:20 Question 5
    38:41 Question 6
    44:40 Question 7
    49:37 Question 8
    53:10 Question 9
    59:18 Question 10
    1:05:25 Question 11
    1:10:04 Question 12
    1:16:03 Question 13
    1:21:03 Question 14
    1:28:43 Question 15
    1:30:35 Bonus Question
    Check the pdf for the questions

    • @arpitkeer8114
      @arpitkeer8114 4 роки тому +1

      Integrate. [Cos^-1x (√1-x^2)]^-1 / Log{1+(sin(2x√1-x^2)/π}

    • @thesardaunatv
      @thesardaunatv 4 роки тому +1

      If you are interested in mathematics here is my videos on sliderule
      m.ua-cam.com/video/ReNFu4meONc/v-deo.html

    • @aashsyed1277
      @aashsyed1277 3 роки тому

      almost

    • @bubunsaha4120
      @bubunsaha4120 3 роки тому

      Sir from where I can download the pdf of those questions ?

    • @ammarkseibi9616
      @ammarkseibi9616 2 роки тому

      In question 4, why did you replace sin(2n) by 1?
      Thank you!

  • @ElReyZero
    @ElReyZero 4 роки тому +60

    BPRP you are a blessing, I have a series test tomorrow and this is helping me a lot to practice!!! Keep up the great content!

  • @ダーリン-o7t
    @ダーリン-o7t Рік тому +7

    omg literally thank you SO much. I know it's been two years since you made this live but it came to my life in the perfect time. You're AMAZING !!!

  • @AskTig4609
    @AskTig4609 2 роки тому +15

    I enjoy watching your video. It's not just because you are good at explaining things but because we can see it in your face that you really enjoy making this video

  • @baseballdude345
    @baseballdude345 2 роки тому +6

    love how enthusiastic this man is about calculus

  • @spammusubi1607
    @spammusubi1607 3 роки тому +20

    This is EXACTLY what I needed. I’m struggling with this topic at the moment

  • @blackpenredpen
    @blackpenredpen  4 роки тому +106

    Can anyone help me with the timestamps? Thank you.

    • @treanungkurmal803
      @treanungkurmal803 4 роки тому +40

      4:38 Question 1
      9:07 Question 2
      14:00 Question 3
      23:40 Question 4
      30:20 Question 5
      38:41 Question 6
      44:40 Question 7
      49:37 Question 8
      53:10 Question 9
      59:18 Question 10
      1:05:25 Question 11
      1:10:04 Question 12
      1:16:03 Question 13
      1:21:03 Question 14
      1:28:43 Question 15
      1:30:35 Bonus Question
      Guys the Check pdf in the description for the question. Give a like if you liked the hard work ❤️

    • @blackpenredpen
      @blackpenredpen  4 роки тому +24

      @@treanungkurmal803 Thank you so much Treanungkur!

    • @treanungkurmal803
      @treanungkurmal803 4 роки тому +19

      @@blackpenredpen Really pleased sir that you replied ❤️

    • @jmr0411
      @jmr0411 4 роки тому

      My professor allows us to bring a notecard to the test and I wrote the series convergence tests table you provided on mine. I'm feeling pretty confident, thanks!

  • @mikaelgonzalez2739
    @mikaelgonzalez2739 4 роки тому +16

    Your good mood is so contagious! Thanks a lot for your clear explanations and giving people like me enjoyment doing this!!

  • @SomethingGamecatAdjacent
    @SomethingGamecatAdjacent Рік тому +2

    This video was incredible. Used it for my exam last week and it was a CRUCIAL piece of my success

  • @kingarth0r
    @kingarth0r 4 роки тому +21

    44:22 thanks for the shout out my guy

  • @robertbrett3350
    @robertbrett3350 2 роки тому +3

    Thank you for your kindness by posting many videos for educational purposes. You are good man !

  • @patrickhaynes2394
    @patrickhaynes2394 4 роки тому +20

    Someone who truly loves math, I found my polar opposite.

  • @adrianoseresi3525
    @adrianoseresi3525 4 роки тому +35

    A truly fine beard my good sir!

  • @roberthaas3376
    @roberthaas3376 9 місяців тому

    Hey! I just wanted to say thank you so much for this stream, my exam is in about 3 hours and I found this gem last night and binged through it. I feel so much more confident now!

  • @delphiaoconnor8544
    @delphiaoconnor8544 Рік тому +1

    watching this in 2023 a day before my calc 2 exam. thank you so much for your videos!! they really help me.
    btw i'm from nazarbayev university, kazakhstan

  • @mr.explisovesnowman8836
    @mr.explisovesnowman8836 4 роки тому +3

    thank you balckpenredpen.............
    for posting this days after my exam....
    but seriously good video

  • @opufy
    @opufy Рік тому +1

    THANK YOU! for that gift note!

  • @skwbusaidi
    @skwbusaidi 4 роки тому +10

    Number 14
    Can also be expressed as sum from 2 to inf of 1/(n^2-1)

  • @tomctutor
    @tomctutor 4 роки тому +20

    Students the _"scary sigma"_ ∑ ☠ takes a lot of practice to master and BPRP has done a marvelous job here putting this material together covering all the various tests you need to know. ✔
    *BonusQ:* LCT: [sin(1/2n)]^2 ,which is monotonic↘, with lim n→∞ of p-conv (1/(2n)^2), let ⌀=1/(2n) so lim ⌀→0 [sin(⌀)/⌀]^2=1.

  • @robertbrett3350
    @robertbrett3350 2 роки тому

    Thanks

  • @amandastandow8912
    @amandastandow8912 2 роки тому

    BLESS! These notes are going to make my homework downright bearable!

  • @rantongl2238
    @rantongl2238 2 роки тому +4

    Bro if I pass my first analysis test in uni it's all because of you. Thank you so much for the content!

  • @glen8826
    @glen8826 2 роки тому +1

    Super proud of myself of going through this start to finish

  • @spb1179
    @spb1179 4 роки тому +3

    Thanks for this, test over it tomorrow!

  • @AngelCampa-im4to
    @AngelCampa-im4to 9 місяців тому

    your amazing!!! you make this really easy to understand and follow along !!

  • @andrekpl7668
    @andrekpl7668 4 роки тому +2

    Great job man

  • @The1RandomFool
    @The1RandomFool 4 роки тому +3

    On the bonus question at the end, a bit of analysis can also be used. You can use the comparison test with the sum of 1/(2*n^2), which means the series converges to a value less than or equal to pi^2/12. The reason for this is because you can use the series expansion of 1 - cos(1/n) to get the sum of 1 - (1 - 1/(2*n^2) + O(1/n^4)), which simplifies to the sum of 1/(2*n^2) - O(1/n^4). It's less than or equal to the sum of 1/(2*n^2).

    • @violintegral
      @violintegral 3 роки тому +1

      Even easier: notice that 1-cos(1/n)=2sin²(1/(2n)). This converges by #9 on this video, which showed that sin²(1/n) converges by the limit comparison test with 1/n². Since sin²(1/n) is always positive and it converges, then it does so absolutely. Since it converges absolutely, then any rearrangement of its terms also converges absolutely, and to the same value. Therefore, the sequence of even terms of sin²(1/n), sin²(1/(2n)), must also converge. Or you could just do limit comparison with 1/n² again lol. You basically did the same thing anyway, but it's even easier if you just use the trig identity so you don't have to worry about the Taylor Polynomial approximations and such.

  • @anstjd_ys
    @anstjd_ys 6 місяців тому

    You are the legend, always the best explanation

  • @violintegral
    @violintegral 3 роки тому +4

    I have a test on Sequences on Series due today (I'm taking Calc 2 online through my local community college since I'm still in high school) so I'm using this video as a final review. I already watched it through once a few months ago when I was teaching myself, but I'm back again!

  • @yzotape529
    @yzotape529 4 роки тому +23

    WHY WAS THIS NOT RELEASED 4 DAYS AGO WHEN I DIDNT HAVE MY CALC 2 EXAM ON FRIDAY
    -purdue engineering student

    • @dylant830
      @dylant830 4 роки тому

      Haha I really could have used this practice before I failed my calc final yesterday :)

    • @jmr0411
      @jmr0411 4 роки тому

      I have mine today luckily

  • @guilhermevolpini6136
    @guilhermevolpini6136 Рік тому +1

    Saved my calc 3 test ❤

  • @alainrogez8485
    @alainrogez8485 4 роки тому +5

    For the bonus, I used Taylor series. Cos u = 1-u^2/2. So 1-cos(1/n) goes to 1/2n^2. Thanks to the p-series, because p is equal to 2 in this one, the bonus serie converges.

  • @pizzy1992
    @pizzy1992 4 роки тому +2

    This was just wonderful :D thanks a lot

  • @dasav6724
    @dasav6724 4 роки тому +34

    Yo blackpenredpen! For your next 100 problem challenge, could you tackle trigonometric equations and identities and stuff?
    Basically, formulas like sinC + sinD, the half angle formulas, and all that good stuff used in simplifying and solving problems.
    Thank you for everything.

  • @krrishmaheshwari4860
    @krrishmaheshwari4860 3 роки тому +1

    13 Question , i think it is conditionally Convergent as |Un|=1/n(3+1/n) where by p series p=1

  • @The1RandomFool
    @The1RandomFool 4 роки тому +4

    For number 3, the root test would work as well, and includes a famous limit (n!)^(1/n) / n as n approaches infinity.

  • @wjrasmussen666
    @wjrasmussen666 2 роки тому

    Another great video!!

  • @OgundipeSamuel-cp6xt
    @OgundipeSamuel-cp6xt Рік тому

    You really motivate me and I wish to meet you in person someday 😊

  • @arpitkeer8114
    @arpitkeer8114 4 роки тому +3

    Integrate. [Cos^-1x (√1-x^2)]^-1 / Log{1+(sin(2x√1-x^2)/π}

  • @nvapisces7011
    @nvapisces7011 Рік тому

    For bonus question, can use the double angle formula to change it to 2sin²(1/2n). Last we recall, there is a similar question earlier where we use limit comparison test for 1/(4n²)

  • @carolynncalin1199
    @carolynncalin1199 Рік тому

    YOU ARE AMAZING!! You are saving my calc II grade in university.

  • @andreasavraam6898
    @andreasavraam6898 3 роки тому +4

    If the ratio test is inconclusive, you might be able to use Raabe's test (of course it's not certain that it'll be conclusive either). You could add it in the notes after the ratio test.

    • @andreasavraam6898
      @andreasavraam6898 3 роки тому

      It basically says that if the ratio limit is equal to 1, calculate the lim of n(1-an+1/an),let's say that this limit is equal to L, then if L>1 then the original series converges,if L

  • @Bravo_L
    @Bravo_L 4 роки тому +1

    This is awesome thanks professor!!!!!!!

  • @WattersZ
    @WattersZ Рік тому

    Abbreviation may change between teachers for the final test explanation (problem 4), but this is very helpful! Thank you bprp

  • @djomoangeingrid6923
    @djomoangeingrid6923 2 роки тому

    I'm currently doing real analysis and this video was soo helpfull thanks so much

  • @PhysicsofAcala
    @PhysicsofAcala 2 роки тому

    your videos are amazing. Thank you.

  • @kiranbarnwal8503
    @kiranbarnwal8503 3 роки тому

    In question no 3 14:00 -2/e is correct as minus sign will remain with 2

  • @sabrinaf4436
    @sabrinaf4436 2 роки тому

    Thank you from Italy!

  • @btsfan69420
    @btsfan69420 3 роки тому +1

    I have my final exam tomorrow. I’m channeling my bprp knowledge before bed with this video

  • @krrishmaheshwari4860
    @krrishmaheshwari4860 3 роки тому +1

    Bonus Question:
    1-cos(1/n)=2sin^2(1/2n) multiply divide by 4n^2 take limit sinx/x=0 as x-->0 we will be left with 1/n^2 variable term which we can take as vn now un/vn=1/2 hence by P series Vn is convergent and so is Un! :)

  • @prudvigorantla930
    @prudvigorantla930 4 роки тому +1

    How to limit X tends to zero sin(X) also tends to zero. In problem no 9

  • @ashleychandler3642
    @ashleychandler3642 Рік тому

    Life saver! Thank you so much.

  • @nicholaschow6389
    @nicholaschow6389 9 місяців тому

    i have my calc 2 final exam in 4 days bro actually saved me

  • @JamesSmith-fl6pd
    @JamesSmith-fl6pd 8 місяців тому +1

    Thank you so much you saved my life!

  • @mirayayna1295
    @mirayayna1295 2 роки тому +1

    From Lebanon 🇱🇧
    Thank you very much❤️

  • @girijasankarmandal1138
    @girijasankarmandal1138 2 роки тому

    Your pdf is very very helpful to me sir thank you for your effort for us.

  • @academicmood
    @academicmood 4 роки тому +23

    Damn you make me miss math

  • @phazonicridley3858
    @phazonicridley3858 3 роки тому +1

    Bonus question answer. Converges by DCT compare it to 1/(n^2) (a convergent series) which is bigger than 1 - cos(1/n).

  • @87AndreasW
    @87AndreasW 4 роки тому +1

    Are you able to give some information about dynamic systems? matrices etc.
    I have this question but unsure what to put as X1, Y1 and X2,Y2
    "David jogs either in the woods or on asphalt. If he jogs in the woods, the probability is 30% that the next jogging trip is also in the forest, while the probability is 70% for the next jogging trip on asphalt.If he jogged on asphalt, the probability is 50% that the next trip is in the woods, and 50% the first trip on asphalt. David jogs his first trip in the woods.
    Find a formula for probability vector k, which describes the probabilities of forest or asphalt on trip k."

  • @cina0rh
    @cina0rh 3 роки тому +1

    This is amazing thank you

  • @nigelsheldon5753
    @nigelsheldon5753 3 роки тому

    Thank you! You're the best!

  • @nicogehren6566
    @nicogehren6566 4 роки тому +1

    very helpfull video thanks Mr. bprp

  • @pierrevieu9997
    @pierrevieu9997 3 роки тому +1

    Ratio test is called d’alembert rule in 🇫🇷

  • @jameskennedy674
    @jameskennedy674 3 роки тому

    This guys dope. I like him!

  • @denisedesireeannaneumann9804
    @denisedesireeannaneumann9804 3 роки тому +1

    Thank you 🌈👌

  • @BrawlN64
    @BrawlN64 Рік тому

    Float vs Natural Number vs Integer Range divided or not by consant vs fractional sets vs OE set vs Complex numbers vs Phasors how fast/ops for convergence vs error cases 1/INF=Infintesimal 10bit 1/INF=0 32bit

  • @mohsinqureshi6526
    @mohsinqureshi6526 2 роки тому

    So nice teaching bro .. thank you so much .... 👍🏼

  • @ayanaxhye
    @ayanaxhye Рік тому +2

    me watching this after getting 50% of them on my homework 🥴

  • @NoName-eh8fz
    @NoName-eh8fz 4 роки тому +2

    I have 2 questions. Im not studying maths yet (Im still in school) so I dont know if my ways of solving are correct. Would be really cool if somebody could verify or show the mistakes.
    Question 12
    arctan(n)

    • @violintegral
      @violintegral 3 роки тому

      Your method for #12 is close but not correct. Notice that arctan(1)=π/4 and arctanx approaches π/2 as x→∞, so arctan(n)

  • @ffc1a28c7
    @ffc1a28c7 2 роки тому +1

    For 12, you can just do direct comparison test with pi/(2x^2) which converges as arctanx is bound by pi/2.

  • @charlesdesouza9313
    @charlesdesouza9313 4 роки тому +3

    what is this useful for? i mean, applications instead of memorizing?

  • @darcash1738
    @darcash1738 Рік тому

    5 can also be done by integral test

  • @kateryna1611
    @kateryna1611 3 роки тому +1

    Thank you so much!!!

  • @anjanamarasinghe6623
    @anjanamarasinghe6623 3 роки тому

    Thank you very much.clear and sweet.

  • @jojodalmangadijojo
    @jojodalmangadijojo 11 місяців тому

    Preparing for analysis 1 exam in IT
    For the number 12 I did a Limit comparison test with 1/n²+1, which converges because it's less than 1/n² which, again, converges because it's a p series where p>1. So from the LCT I got π/2>0, so the 12 converges too. The solving should be correct, so yay I found another way which, to be honest, seems way easier than getting the graph, taking the integral et cetera.

  • @mizelcluett2105
    @mizelcluett2105 4 роки тому +1

    loving the beard!

  • @davida99
    @davida99 3 роки тому

    This is good practice for my final!

  • @ahmedismailfahmy4365
    @ahmedismailfahmy4365 4 роки тому +1

    bonus >> LCT with 1/n^2 , it will converge

    • @riazuddinsheikh3198
      @riazuddinsheikh3198 3 роки тому

      No. It will diverge by LCT taking 1/2n

    • @juice_verse
      @juice_verse 2 роки тому

      @@riazuddinsheikh3198 You mean diverge by using LCT, and comparing by 1/2n

  • @perelium-x
    @perelium-x Рік тому

    26:00 why didnt we do 1/n > 1/(n+3^n)

  • @negar1370
    @negar1370 2 роки тому +1

    Thank you so much!

  • @useruser400
    @useruser400 4 роки тому +1

    I come here for the T-shirts. Best on UA-cam. 🤓🤪

  • @subhajit201
    @subhajit201 3 роки тому +1

    Only if I had u as my maths teacher during my grad.

  • @PimpMatt0
    @PimpMatt0 3 роки тому +1

    I had to learn this in a week over summer 😩 damn now I forgot it all

  • @girijasankarmandal1138
    @girijasankarmandal1138 Рік тому

    n4+3n/4n3-2n+1 divergence or convergence

  • @lichen420
    @lichen420 4 роки тому +1

    I thought that if cos(0) is 1 and cos(1) is about 1/2 you would be adding closer and closer to one and the sum would be divergent.

  • @xgs660
    @xgs660 4 роки тому +1

    Wow I have an exam of series tomorrow thanks😂😂😂❤

  • @luciennyuba4980
    @luciennyuba4980 Рік тому

    Thank you professor, keep up the good work

  • @sbarz106
    @sbarz106 2 роки тому +2

    Hey, thank you for your videos, just the link of the file says it got blocked by bitly, do you have another one?

  • @johnholemans5655
    @johnholemans5655 2 місяці тому

    Hi, your video is very nice.
    I'm unable the retrieve the files in the description. Do you know how amd where can I get one? If it is still possible.

  • @alainrogez8485
    @alainrogez8485 2 роки тому

    Q bonus : use Taylor series.
    1 - cos (1/n) = 1 - 1 + 1/n^2 + o(1/n^4)
    Equivalent to 1/n^2 serie which converges.

  • @3sportoXD
    @3sportoXD Рік тому +1

    I got a doubt for question 2: shouldnt 'a' suppose to be 1 instead of 7/8 . so I end up with 1/ (1-7/8) = 8 . so the series converges to 8

  • @AMIT_OP
    @AMIT_OP 4 роки тому +1

    Nice beared sir

  • @muroderepolho69
    @muroderepolho69 3 роки тому +1

    Thank you :D

  • @abdellatifdz8748
    @abdellatifdz8748 3 роки тому

    I love this video

  • @wuznab5109
    @wuznab5109 Рік тому +2

    I must be extremely dumb, but I still don't understand when and what types of series to apply to problems. As far as i can tell there is no general rule in knowing which one to use. It all has to be memorized??? Can someone please help me out, there has to be some pattern here i'm missing?

  • @sagnikchakravarty
    @sagnikchakravarty 4 роки тому +1

    Isnt the 3rd question going to be solved by Leibnitz test cause the de alembert he is using is only for the series were the terms are not of negetive signs

  • @fun_engineering5710
    @fun_engineering5710 4 роки тому +1

    Hi bprp
    When do you make live streams; I want to participate