Alternating Series Test

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  • เผยแพร่เมื่อ 29 มี.ค. 2018
  • This calculus 2 video tutorial provides a basic introduction into the alternating series test and how to use it to determine the convergence and divergence of a series.
    Integral Test For Divergence: • Calculus 2 - Integral ...
    Remainder Estimate - Integral Test:
    • Remainder Estimate For...
    P-Series:
    • P-series
    Direct Comparison Test:
    • Direct Comparison Test...
    Limit Comparison Test:
    • Limit Comparison Test
    _________________________________
    Alternating Series Test:
    • Alternating Series Test
    Alternate Series Estimation Theorem:
    • Alternate Series Estim...
    Absolute & Conditional Convergence:
    • Absolute Convergence, ...
    The Ratio Test:
    • Ratio Test
    The Root Test:
    • Root Test
    __________________________________
    Series Tests - Practice Problems:
    • Calculus 2 - Geometric...
    Taylor & Maclaurin Polynomials:
    • Taylor Polynomials & M...
    Taylor's Remainder Theorem:
    • Taylor's Remainder The...
    Power Series - Interval Convergence:
    • Power Series - Finding...
    Power Series - Derivatives & Integrals:
    • Power Series - Differe...
    ___________________________________
    Calculus Final Exam and Video Playlists:
    www.video-tutor.net/
    Full-Length Videos and Worksheets:
    / collections

ความคิดเห็น • 202

  • @TheOrganicChemistryTutor
    @TheOrganicChemistryTutor  ปีที่แล้ว +10

    Next Video: th-cam.com/video/FkUrAgBzAZo/w-d-xo.html
    Final Exams and Video Playlists: www.video-tutor.net/

  • @itllbeokay7112
    @itllbeokay7112 5 ปีที่แล้ว +830

    You've got this. Stop reading comments and go study to ace that test.
    Or pass that test whatever your goal is

    • @SyrinSlava
      @SyrinSlava 4 ปีที่แล้ว +33

      At this rate, my only chance is a C lmao.

    • @Yo-pn9qp
      @Yo-pn9qp 4 ปีที่แล้ว +1

      Thanks boo

    • @zozozoz2460
      @zozozoz2460 3 ปีที่แล้ว

      اي صدك ما تنفهم

    • @zozozoz2460
      @zozozoz2460 3 ปีที่แล้ว +2

      😂😂😂😂😭😭

    • @ignantxxxninja
      @ignantxxxninja 3 ปีที่แล้ว +1

      @it'll be okay & @Sleeve Them All that was very motivating

  • @meerasrinivasan9481
    @meerasrinivasan9481 3 ปีที่แล้ว +199

    You seriously are the greatest of all time. I had Calc 1 last semester and watched your videos instead of lecture because you explain things so clearly and do the algebra really well. Aced that class thanks to you! Now acing calculus 2 with your videos, once again. Wishing you the most success and happiness!! You have such a big impact on math students - esp ones like me who genuinely never thought I'd even get through calc 1 let alone 2!

  • @hsc4648
    @hsc4648 4 ปีที่แล้ว +585

    Seems so easy when you look at his video but by the time I get to my university text book lol the difficulty of the problems are totally on another level.

    • @sofir9400
      @sofir9400 4 ปีที่แล้ว +28

      right its completely diff lmao

    • @kaylao.7688
      @kaylao.7688 4 ปีที่แล้ว +5

      @@sofir9400 felt that...

    • @ferry6700
      @ferry6700 4 ปีที่แล้ว +20

      Univ text book is shit :'(

    • @ryzurrin
      @ryzurrin 3 ปีที่แล้ว +3

      exactly the case :(

    • @AbdoAhmed-qw3le
      @AbdoAhmed-qw3le 3 ปีที่แล้ว +6

      @@kaylao.7688 never knew shit could be so expensive 😭😭😭

  • @luciogaribay4321
    @luciogaribay4321 4 ปีที่แล้ว +103

    I’m currently taking calculus 2 in the summer and it is brutal but these videos keep me going. They make everything more simple to learn.

    • @chrismason1530
      @chrismason1530 ปีที่แล้ว

      Same

    • @leif1075
      @leif1075 ปีที่แล้ว

      Why is it brutal?

    • @potatotuna7988
      @potatotuna7988 ปีที่แล้ว

      @@leif1075 calculus can be pretty hardddd

    • @calebfoxschool
      @calebfoxschool ปีที่แล้ว +3

      @@leif1075 As someone who took Calc 1 over the summer, it's just a lot to take in at once. With jumping all around from integral techniques, physics problems, parametric/polar equations, and now series/sequences, I can imagine it would be hard to grasp all the concepts in a short amount of time.

    • @ash-lo2dc
      @ash-lo2dc ปีที่แล้ว

      @@leif1075 summer semesters are kinda short iirc

  • @ahmedjamshaid7727
    @ahmedjamshaid7727 3 ปีที่แล้ว +88

    Just amazing, and I couldn't understand my professor's 4 hours of lectures

  • @maameabena514
    @maameabena514 3 ปีที่แล้ว +21

    You're the best thing that ever happened to my college career

  • @its1haruka1dayo
    @its1haruka1dayo 3 ปีที่แล้ว +6

    I was about to cry because I didn't understand a word until I watched this video
    THANK YOU THREE YEARS LATER!!

  • @nurayim6295
    @nurayim6295 ปีที่แล้ว +4

    Words can't expess how I'm grateful. Our teacher just reads off the presentations during lectures and I don't understand anything, but thanks to you I'm easily passing all of the quizes, homeworks and mid/end term exams. Got only the final exam left to pass, thanks a lot for saving my degree😭❤

  • @zhouj8634
    @zhouj8634 5 ปีที่แล้ว +31

    I love all of your videos. They help me a lot. I just want to point out one thing in this video: at the 6 minutes mark, you said :”The test is failed, so the series diverges.” Alternating series test just can prove convergence, can not prove divergent. So the conclusion should be inconclusive. If the test failed, we should use other test to define convergence or divergent.

    • @armandoolmos1816
      @armandoolmos1816 4 ปีที่แล้ว +1

      Zhou J This should be pinned as top comment so anyone learning the A.S.T would know that it only proves convergence.

    • @griffinewine615
      @griffinewine615 4 ปีที่แล้ว

      This is correct

    • @reemabedair9223
      @reemabedair9223 2 ปีที่แล้ว +2

      I know I'm late, but he said in the beginning of the video that if the first test fails, you can consider that as automatically diverging

    • @ARTDEVGRU247
      @ARTDEVGRU247 ปีที่แล้ว

      Yea i picked up on that

  • @ammaralsawai7724
    @ammaralsawai7724 5 ปีที่แล้ว +96

    You should be the one I pay

    • @itllbeokay7112
      @itllbeokay7112 5 ปีที่แล้ว +10

      You can do that by watching his ads:)

  • @shijialiu8678
    @shijialiu8678 3 ปีที่แล้ว

    Thank you so much! This is extremely helpful and your demonstration is so clear!

  • @joshuaabbott7134
    @joshuaabbott7134 5 ปีที่แล้ว +37

    Your videos make so much more sense than my professor! Thank you!!!

  • @hibanazar9039
    @hibanazar9039 2 ปีที่แล้ว +1

    The methods are way more easier.
    Thank you so much.

  • @genogurirab8061
    @genogurirab8061 2 ปีที่แล้ว +2

    You are talented really the absolute king

  • @rotemlv
    @rotemlv 3 ปีที่แล้ว +6

    10:21
    n has to go from 2 here as the denominator is undefined at n = 1.

  • @abdulrahmanyasser3897
    @abdulrahmanyasser3897 6 ปีที่แล้ว +1

    ...thanks dude u r awesome ...i really understood math on ur hands

  • @chrisp2639
    @chrisp2639 11 หลายเดือนก่อน +8

    Between your videos and Paul's Notes for additional practice problems, I have an A+ in calculus 2. Thank you!

  • @jameson409
    @jameson409 4 ปีที่แล้ว +26

    who else is watching this in preparation for the AP calculus exam

    • @bulidrians2182
      @bulidrians2182 3 ปีที่แล้ว +2

      not me cuz ap calc is for nerdz.

  • @frankimhof8124
    @frankimhof8124 5 ปีที่แล้ว

    man I love your videos. They're so clear and easy to follow. Thanks a lot!

  • @adabujiki
    @adabujiki 4 ปีที่แล้ว +2

    Lol this guy knows my deep frustrations with this concept-- I COULD NEVER FIGURE OUT WHAT A-sub-n was in the function... turns out it was the quotient 1/n... when one sees a bunch of "n" variables everywhere it is hard to tell how to solve it. THANKS BRO... be nice to show ur face one day so we can profile u and make assumptions of u

  • @FaisalAl-Edaily
    @FaisalAl-Edaily หลายเดือนก่อน

    I think you deserve way more than 7.88M Subs, Like seriously you explain so good I understand most of the stuff you explain (Not everything since i'm a 9 year old)

  • @rap33r100
    @rap33r100 5 ปีที่แล้ว +59

    It would be more accurately described as it needs to fail the divergence test. As passing the test implies its divergent. Other than that excellent video

    • @eric693
      @eric693 5 ปีที่แล้ว +5

      One of my classmates was confused over the meaning of passing or failing the test. Although it is kind of odd to say "failing" when it satisfies the conditions, but in this context, it would make sense to say failing the Divergence Test. It could be put in a way like the following: A checkpoint on the road to pick off a specific car. If a car doesn't satisfy the conditions, then it moves on -- passing the checkpoint. Whereas if a car meets the condition, it gets pulled off and fails to pass the checkpoint. I tried explaining it like that to her, but she doesn't seem to get it still. . .I mean both passing and failing makes sense in their own way.

    • @niche5006
      @niche5006 5 ปีที่แล้ว +2

      @@eric693 I think of it like this: when a series passes a test then there is no need for another test because you have found the answer. Likewise, when you fail a test, you need to try another test to find convergence or divergence.

    • @mreleven7826
      @mreleven7826 5 ปีที่แล้ว +3

      JMac he is correct . If u pass a drug test . What does that mean?

    • @angebomb
      @angebomb 4 ปีที่แล้ว +1

      YES! It took me an hour to realize that he was implying two different things lol

    • @lancematteson2416
      @lancematteson2416 3 ปีที่แล้ว

      That tripped me up for a bit! I had to go back and double check my notes; I thought I might have wrote the Divergence Test incorrectly! Once I realized he more meant that "this meets the first condition" I was able to get back on track.

  • @Just_A_Transperson
    @Just_A_Transperson 6 หลายเดือนก่อน

    Thank you so much. You got me a 5 on AP calc, and you care getting me through calc 2 in collage.

  • @scoot115
    @scoot115 3 ปีที่แล้ว +6

    Organic Chemistry Tutor > Every college professor

  • @rajendramisir3530
    @rajendramisir3530 5 ปีที่แล้ว +34

    Interesting: Harmonic series diverges by p-series test while alternating harmonic series converges by alternating series test.

    • @nicholasmaloof8378
      @nicholasmaloof8378 4 ปีที่แล้ว +3

      This tripped me up a bit

    • @Zephyr-tg9hu
      @Zephyr-tg9hu 4 ปีที่แล้ว +13

      This has always made little intuitive sense to me.
      Reminds me of some wise words once spoken by Von Neumann: "Young man, in mathematics you don't understand things. You just get used to them."

    • @chrischika7026
      @chrischika7026 3 ปีที่แล้ว

      bAy-Zesd

    • @kylejohnson1248
      @kylejohnson1248 2 ปีที่แล้ว +1

      Because it’s conditionally convergent, the convergence is caused by the negative.

    • @xEqualsRandom
      @xEqualsRandom ปีที่แล้ว +1

      ​@@kylejohnson1248 I thought this video was a bit confusing because it doesn't mention convergence vs conditional convergence

  • @MrMarkgyuro
    @MrMarkgyuro 4 ปีที่แล้ว +1

    best video to understand this topic

  • @candicechita9789
    @candicechita9789 ปีที่แล้ว +1

    You never disappoint dude🥹

  • @marmedrano4365
    @marmedrano4365 3 ปีที่แล้ว

    I love this man so much.

  • @yuxichi4245
    @yuxichi4245 4 ปีที่แล้ว

    IT IS REALLY HELPFUL!

  • @abidashaheen819
    @abidashaheen819 3 ปีที่แล้ว +1

    Great lecture 👍🏻👍🏻👍🏻👍🏻

  • @mr.prince8701
    @mr.prince8701 6 ปีที่แล้ว +2

    Great video as always.

    • @adios04
      @adios04 3 ปีที่แล้ว

      thanks!

  • @onur7192
    @onur7192 5 ปีที่แล้ว +1

    thx you so much my teacher it gonna be good for midterm1 :D

  • @nothingtoxicated5937
    @nothingtoxicated5937 4 ปีที่แล้ว +5

    You deserve more subscriber than Khan academy

  • @_towards_destination
    @_towards_destination 2 ปีที่แล้ว

    You are a pro man ♥️♥️ God bless you

  • @fahadsaleem5727
    @fahadsaleem5727 5 ปีที่แล้ว

    bundle of thanks

  • @NabharajShrestha
    @NabharajShrestha 5 ปีที่แล้ว

    You are aweosome...
    Thank you soo much...

  • @sofiaizaguirre5779
    @sofiaizaguirre5779 6 ปีที่แล้ว +1

    thank you so much

  • @shyamyadla3515
    @shyamyadla3515 5 ปีที่แล้ว

    Great job

  • @mathgmathg923
    @mathgmathg923 6 ปีที่แล้ว +6

    You are AWESOME!!!!!

    • @adios04
      @adios04 3 ปีที่แล้ว

      Thanks!

  • @theplasmatron3306
    @theplasmatron3306 6 หลายเดือนก่อน

    This awesome, I appreciate it. Thank you!

  • @madhurakulkarni1880
    @madhurakulkarni1880 5 ปีที่แล้ว

    Thank you so much sir ......

  • @dilkinirasha9612
    @dilkinirasha9612 2 ปีที่แล้ว +1

    You can teach all the semesters within one semester.😍

  • @cold_scene
    @cold_scene ปีที่แล้ว

    you are amazing dude

  • @colinjaros1710
    @colinjaros1710 3 ปีที่แล้ว

    Thank you !

  • @uchennaobi5985
    @uchennaobi5985 5 ปีที่แล้ว +2

    You are GOD like at teaching

  • @ahankurdi1745
    @ahankurdi1745 3 ปีที่แล้ว +2

    You do better than all of my professors. You desire golden rewords. ❤️

  • @tsholocarly4786
    @tsholocarly4786 ปีที่แล้ว

    Such a genius😩

  • @aaronfister2129
    @aaronfister2129 3 ปีที่แล้ว

    this mans doesn't miss

  • @alifaziz3539
    @alifaziz3539 2 ปีที่แล้ว

    you are great ....😊 thank u so much

  • @nikkim8098
    @nikkim8098 6 ปีที่แล้ว +1

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    • @adios04
      @adios04 3 ปีที่แล้ว

      your very welcome!

  • @farwamalik3028
    @farwamalik3028 2 ปีที่แล้ว

    Amazing 👌

  • @bernadettelola638
    @bernadettelola638 3 ปีที่แล้ว

    Thank you

  • @harshitbhandi5118
    @harshitbhandi5118 3 ปีที่แล้ว +1

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  • @ahankurdi1745
    @ahankurdi1745 3 ปีที่แล้ว

    Loved itt ❤️

  • @SilentJnation
    @SilentJnation หลายเดือนก่อน

    God bless you. Calc 2 final is tomorrow morning.

  • @lootingpig9713
    @lootingpig9713 5 ปีที่แล้ว +1

    gud stuff broski

  • @twinbruisesonmyshins
    @twinbruisesonmyshins 6 หลายเดือนก่อน

    this video actually saved my fucking life, i take cal2 and sequences/series are the last chapter before exams and they absolutely decimate me. i worked for eight hours on an assignment thats majority series and barely made any progress

  • @soner8780
    @soner8780 5 ปีที่แล้ว

    thanks

  • @dhyeyranpara2351
    @dhyeyranpara2351 ปีที่แล้ว

    not gonna lie, you should start your own virtual university. you just too good.

  • @rajendramisir3530
    @rajendramisir3530 5 ปีที่แล้ว

    Must watch video for a variety of examples on each technique, topic or concept. I particularly like the cos(2pi) effect of creating an alternating series. I suppose sin(2pi) will have a similar effect.

  • @A1T6J
    @A1T6J ปีที่แล้ว

    Thanks Bro

  • @frankvalen2147
    @frankvalen2147 3 ปีที่แล้ว +1

    why cant I just plug number like 1 in that question that has ln(n+1)/n+1

  • @georgesadler7830
    @georgesadler7830 2 ปีที่แล้ว +1

    Professor Organic Chemistry Tutor, thank you for an excellent video/lecture on the Alternating Series Test in Calculus Two. The Alternating Series Test is not a difficult test to understand, however checking for convergence can be problematic. This is an error free video/lecture on TH-cam TV with the Organic Chemistry Tutor.

  • @kafianan6586
    @kafianan6586 5 ปีที่แล้ว

    {(1-lnx)/x^2}... How this function is increasing in the interval [1,e) ?
    Moreover, we get the max value of function when limit of [x] tends to 0... If I am wrong please make me correct.. Thank you

  • @subodh3797
    @subodh3797 ปีที่แล้ว

    thanks bro

  • @frka3176
    @frka3176 3 ปีที่แล้ว

    Can you really use L'Hôpitals rule at 5:40? I've always learned that functions need to be continuous for the derivative to exist, and normally I don't think you would say that a function defined on non compact set of ellements is continuous?

  • @mohammedalnasri6574
    @mohammedalnasri6574 5 ปีที่แล้ว

    legend

  • @energy9442
    @energy9442 2 ปีที่แล้ว

    thank u

  • @Eric-oe6vd
    @Eric-oe6vd 4 ปีที่แล้ว +1

    Thanks, better than my prof x100

  • @LL-kn1de
    @LL-kn1de 6 ปีที่แล้ว

    Thank you!!!!!!!!!!!!!

    • @adios04
      @adios04 3 ปีที่แล้ว

      your welcome

  • @mpilow9463
    @mpilow9463 4 ปีที่แล้ว

    very useful video, Now I know Im alternating

  • @0Saqia0
    @0Saqia0 3 ปีที่แล้ว

    thank you x

    • @adios04
      @adios04 3 ปีที่แล้ว

      no problem

  • @RcReventon
    @RcReventon 5 ปีที่แล้ว

    for the ln(n)/n finding if the function decreases, why do we say that one of the critical points is 0 when setting the denominator equal to 0 will cause an indeterminate form?

    • @richie1603
      @richie1603 5 ปีที่แล้ว

      I think because its indeterminate , you then move on to the next one

  • @memevideos7461
    @memevideos7461 ปีที่แล้ว +1

    so you don't test if lim n-> infinity (whole expression using alternator) = 0 before using this alternating series test?

  • @bychyke9581
    @bychyke9581 4 ปีที่แล้ว

    The question second to last: (ln/n) is divergent by the direct comparison test.

    • @shravipujari8672
      @shravipujari8672 3 ปีที่แล้ว

      No actually the test fails if we use direct comparison method as it is said that if summation an and summation bn are series of positive terms it should satisfy the condition that is
      1) summation bn is convergent then only summation an is convergent.
      2) if summation an is divergent then summation bn is divergent.... Nd in ln(n) / n.... 1/n diverges by the p series test but it is not following the giving condition which is said to be satisfied.

  • @pranav-the-vagabond
    @pranav-the-vagabond 4 ปีที่แล้ว +1

    is it ok to differentiate numerator and denominator saperately?
    If yes, what do we get on differentiating them separately ?

    • @dev217
      @dev217 4 ปีที่แล้ว +2

      Differentiating the numerator and denominator separately is for L'Hopital's rule. When you get a limit in form inf/inf you can use L'Hopital rule to get a new function to work with.

  • @ZkdlinXO
    @ZkdlinXO 5 หลายเดือนก่อน

    12:38 why we didn't use p series for 1/n which is divergent?

  • @wolfie6175
    @wolfie6175 3 ปีที่แล้ว +1

    we had assumed that an>0 but in the second example the denominator is negative for the first term which makes the fraction negative :/

  • @Adam-de8yi
    @Adam-de8yi ปีที่แล้ว

    4 minutes it took me to understand a concept that my lecturer spent 2 hours discussing.

  • @batuhank.758
    @batuhank.758 3 ปีที่แล้ว

    why didn't you use absolute convergence after conditionally convergence?

  • @highermaths
    @highermaths 2 ปีที่แล้ว

    helpful

  • @suturesgh4342
    @suturesgh4342 ปีที่แล้ว

    Please what if its raised to the power n-1

  • @sabilakensawitri3103
    @sabilakensawitri3103 4 ปีที่แล้ว

    and how to know the sum of series if its converge?

  • @LA-cm9uo
    @LA-cm9uo 3 หลายเดือนก่อน

    Thanks, in my university this topic goes under Calculus 1 still

  • @faizamia9341
    @faizamia9341 หลายเดือนก่อน

    i love u thanks!

  • @alaazingi5784
    @alaazingi5784 2 ปีที่แล้ว +2

    i owe this guy my universitie's tuition

  • @user-vo2zv8nl7c
    @user-vo2zv8nl7c ปีที่แล้ว

    Good

  • @wiwiwang8191
    @wiwiwang8191 ปีที่แล้ว

    I love you.

  • @lewiimetube4369
    @lewiimetube4369 2 ปีที่แล้ว +1

    Can the 1st condition be met and the 2nd one fail? Are there situations like those?

    • @JesusMartinez-zu3xl
      @JesusMartinez-zu3xl 2 ปีที่แล้ว +1

      both conditions need to be met in order for this series to be convergent. I know im late. lmfao.

  • @eduardogomez3653
    @eduardogomez3653 3 ปีที่แล้ว

    Did the series actually decrease in the first example because I thought n=1 equals -1 not 1 like he put

  • @Dylan-ye7jb
    @Dylan-ye7jb 2 หลายเดือนก่อน

    cant believe im watching this video for a differential equations exam I took calc 2 an entire year ago i hate school so damn much

  • @ultra3963
    @ultra3963 4 ปีที่แล้ว +2

    What if the limit is equal to 0, but it isn’t decreasing? Would it be convergent or dirvergent?

    • @reengaesh7545
      @reengaesh7545 4 ปีที่แล้ว

      Ultra Then I Think it will be divergent Bcz it can’t be convergent since both conditions are not fulfilled

    • @PrecisionCSGO
      @PrecisionCSGO 4 ปีที่แล้ว +1

      same, i was wondering this too!

    • @ARTDEVGRU247
      @ARTDEVGRU247 ปีที่แล้ว

      Divergent, because for convergence, it must meet both conditions.

  • @jaytao8124
    @jaytao8124 5 ปีที่แล้ว

    In the last problem, I tried doing divergence test and applied L'Hopital's Rule for cos(npi)/n... I then got DNE as my answer??? Wouldnt it diverge instead?

    • @sarahkamal2585
      @sarahkamal2585 5 ปีที่แล้ว +1

      I think it's because you are supposed to get the limit of An only which is (1/n). the cos(pi*n) is like (-1)^n. You can only apply the divergence test for positive series, therefore you wont get the right answer if u take the limit including the cos(pi*n). that's why we use this alternating test

  • @Hello_am_Mr_Jello
    @Hello_am_Mr_Jello 3 ปีที่แล้ว +3

    Anyone from Morocco?

  • @leoking2716
    @leoking2716 4 ปีที่แล้ว +1

    MY MY MY ==LEGEND

  • @eduardohuerta-mercado1353
    @eduardohuerta-mercado1353 5 ปีที่แล้ว +6

    Any UC Berkeley student taking Math 1B?

  • @zachh6868
    @zachh6868 3 ปีที่แล้ว +1

    I don't understand how my professor can teach the exact same thing, with the same visuals, and I don't get it. I watch your video, and I connect the dots. I can't believe I'm only paying for the degree while getting my education from TH-cam

  • @MrPotaatooo
    @MrPotaatooo 4 ปีที่แล้ว

    for the last example: what if it was sin(n.pi) instead of cos(n.pi)

    • @askngunduz1776
      @askngunduz1776 2 ปีที่แล้ว

      it would just be 0 then.
      sin(pi)=0 , sin(2pi)=0 ...
      well i guess im too late to answer this but still :D

  • @richardfrederick1885
    @richardfrederick1885 2 หลายเดือนก่อน

    If you apply the AST with when An=1/n, then An goes to zero and it passes that part of the test. However, we know that 1/n is the harmonic series which is known to be divergent. There seems to be a contradiction here. How can it both approach zero and be divergent? Does it truly pass the test or not?

    • @pag651
      @pag651 หลายเดือนก่อน

      By the AST the alternating harmonic series (-1)^n (1/n) converges as the limit of the sequence, 1/n as n approaches infinity is zero, fulfilling the first criteria. The second criteria states that each iteration of the sequence must be smaller than the predecessor, which is also true for 1/n for the AST. Since those two criteria are fulfilled, it must mean that the alternating harmonic series (-1)^n (1/n) converges.
      However, the harmonic series in itself is divergent. It is true that the harmonic series 1/n approaches zero, and by the nth-term test, it doesn't fulfill the criteria for divergence. However, just because 1/n approaches zero does not mean it is automatically convergent, you must utilize other tests in order to see if the series is divergent or convergent. Imagine the nth-term as being the most general and broad filter that removes any series in which its sequence never approaches zero. For the case of harmonic series, if you take the integral of 1/n from 1 to b, in which b represents infinity, 1/n becomes ln(n). By the second FTC, the integral is represented by F(b) - F(1), in which F represents the antiderivative, ln(n). If we plug in infinity for n, realize that ln(∞) - ln(1) goes on to infinity, thus making the harmonic series 1/n divergent as it never converges to a definite value.