Choosing Which Convergence Test to Apply to 8 Series

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  • Опубліковано 19 лис 2024
  • Deciding which convergence test to apply to a given series is often the hardest part of the unit on series convergence. In this video, I'm going to loosely walk through some larger strategies for picking and choosing the method, focusing on 8 different series and 8 different methods:
    Geometric Series
    Integral Test
    Divergence Test
    Alternating Series Test
    Comparison Test
    Limit Comparison Test
    Ratio Test
    Root Test
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КОМЕНТАРІ • 244

  • @diatom333
    @diatom333 4 роки тому +1148

    this guys speaks so enthusiastically about this subject while I'm stressing about my exam lol

    • @DrTrefor
      @DrTrefor  4 роки тому +130

      Haha, good luck!

    • @griffisme4833
      @griffisme4833 3 роки тому

      @Oakley Christopher Go to hell scammer

    • @griffisme4833
      @griffisme4833 3 роки тому

      @Draven Callan Go to hell bot #2

    • @braket120
      @braket120 3 роки тому

      Same

    • @lennoxbaylor8155
      @lennoxbaylor8155 3 роки тому

      i know Im randomly asking but does anyone know of a tool to log back into an instagram account?
      I was stupid lost the password. I would appreciate any tricks you can give me

  • @fadelalmobark1932
    @fadelalmobark1932 5 років тому +408

    1 hour till my final for calc2 , guys this course is heavy af
    4 years later: I am process Engineer working @ Neom now and can tell you I use 0 of this course in my work 😂

    • @colejackson7487
      @colejackson7487 4 роки тому +21

      Fadel Almobark 4 months later I’m here for the same reason. Due at midnight tonight lol

    • @justinbieber8270
      @justinbieber8270 4 роки тому +7

      @Pete My final is in 2 days

    • @faya943
      @faya943 3 роки тому +3

      1 year later, I’m here too

    • @fadelalmobark1932
      @fadelalmobark1932 3 роки тому +1

      @@faya943 good luck

    • @ujjal979
      @ujjal979 3 роки тому +3

      i am here before half an hour

  • @juliahicksfav
    @juliahicksfav 4 роки тому +245

    I appreciate the enthusiasm. Helps when I'm watching this at midnight for some last-minute cramming. Very helpful, thank you!

  • @1187624
    @1187624 3 роки тому +77

    When your teacher explains 2 hours for one type of convergence test, this video explains 8 of them for only 12mins..... Thank you for uploading this video! Helped a lot !

  • @henrykretschmer7711
    @henrykretschmer7711 5 років тому +148

    Dr. Bazett if you were my calc professor I'd have an A. You explained the ratio test as an extended version of the geometric test and concisely explained the difference when to use the direct vs limit comparison tests! Thank you for this!!!!

  • @arthurwritis9003
    @arthurwritis9003 3 роки тому +48

    This is one of the most concise and efficient review videos of series/sequences I've come across in my late-night-before-exam cram

    • @filmout8035
      @filmout8035 Місяць тому

      fuck yeah "late-night-before-exam cram"

  • @mohsinmahdi1824
    @mohsinmahdi1824 6 місяців тому +3

    Well Im a lecturer at University of Karbala ( Iraq) and I sent this video to my student cause its simple method to realize which test of series you should choose . thanks to you

  • @MostDopeLastYear
    @MostDopeLastYear 5 років тому +57

    this video is fireeeee my tests in 2 hours this is exactly what i needed

  • @doofus_robot7287
    @doofus_robot7287 3 роки тому +6

    I want to be as excited about anything in my life as this guy is about convergence testing

  • @kwanele1253
    @kwanele1253 2 місяці тому +1

    I needed this video. Deciding on a convergence test has been a nightmare. I have enough time to practice these approaches, before my exam, and I am confident after this video. I grateful

  • @elenalopez9986
    @elenalopez9986 2 роки тому +3

    I have a series test now and I didn’t understand how to differentiate them til now thank you

  • @nutritionbyelsa
    @nutritionbyelsa 7 місяців тому +1

    great great great! thank you so much also thank you for your elevated energy in this question, feels so much healthier and happier to be learnign from someone so excited to share this :)

  • @luna9200
    @luna9200 3 роки тому +14

    Correction: For the series on the bottom right at 0:25, I think you mean n=2 to infinity, not n=1 to infinity. n=1 entails dividing by 0.

  • @filmout8035
    @filmout8035 Місяць тому

    Yk it's a quality video when it's helping out student even 5 yrs after uploading!

  • @dayssalmon-te6430
    @dayssalmon-te6430 6 місяців тому +1

    This is seriously one of the best structured math videos Ive seen, so damn useful. Well done!

  • @stevenogbuehi3846
    @stevenogbuehi3846 3 місяці тому

    This was a very good video in helping folks understand why they should pick or have to use one test over the other. Very deliberate and clear. Excellent work!

  • @ajon5742
    @ajon5742 2 місяці тому +1

    Dr Trefor, I love calculus but conv/diver series was my least favorite. I saw this video some yrs ago and understood the whole thing. I always felt bad for not coming back to thank you🙁. Just logged in to say, THANK YOU SO MUCH! from Scadinavia

  • @hkcmathtutorial2404
    @hkcmathtutorial2404 3 роки тому +1

    I searched Many Many channels, Finally i got the greatest among all🙏🙏🙏🙏

  • @isackvaquera6651
    @isackvaquera6651 2 роки тому +2

    Your voice makes me feel like I can actually learn this course

  • @kiran10110
    @kiran10110 3 роки тому +5

    This was so helpful oh my gosh!! I was so stressed about choosing the right test to use during my exams and this really cleared things up!!

  • @rvmishra9881
    @rvmishra9881 3 роки тому +4

    I just wanted to know what different tests are there.
    He just served my purpose 😍, without actually knowing it.

  • @RosemarieFelimon
    @RosemarieFelimon 3 роки тому +8

    Thank you, Dr. Bazett for creating helpful videos. The quality of your production is amazing. I wish to learn more from you. I hope to make videos similar to yours.

  • @morevrai
    @morevrai 24 дні тому

    it’s been a while since I’ve done calc, but this video helped me review the topic ty!

  • @darshandhande8903
    @darshandhande8903 5 років тому +5

    Exactly what I was looking for. Please make another video discussing more examples.

  • @Virbox
    @Virbox 6 місяців тому

    1) Divergence test:
    lim a(n) =/= 0 ==> series diverges
    2) Comparison test (to p-series/geometric series):
    a(n) a(n) converges
    3) Limit comparison test:
    lim (a(n) / b(n)) = c > 0
    b(n) converges ==> a(n) converges
    4) p-series & geometric series:
    4a) p-series:
    Σ(1/n)^p converges p > 1
    4b) Geometric series:
    Σa*q^(n-1) =
    { a/(1-q) if |q| < 1
    { diverges if |q| >=1
    5) Integral test:
    Integral from 0 to oo f(x)dx converges ==> Σf(n) converges
    6) Alternating series test:
    Σ(-1)^(n-1) * b(n)
    if b(n) > 0, decreasing, lim b(n) = 0
    then series converges
    7) Root test:
    lim root(n, a(n)) = L (if L is finite, series converges)
    8) Ratio test (d'Alembert) (good for factorials & exponents):
    lim a(n+1)/a(n) = L
    if L < 1 ==> series converges absolutely
    if L > 1 ==> series diverges
    if L = 1 or doesn't exist, use other test

  • @ernestezekieljoybetts2088
    @ernestezekieljoybetts2088 3 роки тому +1

    favourite math teacher, best graphics 👌

  • @RayWalker-pythonic
    @RayWalker-pythonic Рік тому +6

    I wished he explained where he got that 1/25 from on that first geometric series. "I can pull out 2 factors of 5..." isn't quite clear. Just a random 2 factors?

    • @xXxXxXxAllianaxXxXxX
      @xXxXxXxAllianaxXxXxX 7 місяців тому +4

      When he goes over the solution to the geometric problem, notice how the 5 has a power of n +1 and not the n - 1 ? He means you need to “lower” that power to the n - 1 for it to nicely match the numerator. So what will bring the n + 1 to the n-1? Remove 5 twice. Aka you remove a 1/25 from the original problem.

  • @gabee4216
    @gabee4216 8 місяців тому +1

    We love you Dr. Bazett!

  • @orwelliannonsense6566
    @orwelliannonsense6566 6 місяців тому

    Thank you for this wonderful video which gives a summary of convergence test techniques. I also like the energy I feel when I watch your videos.

  • @danysikavya7327
    @danysikavya7327 3 роки тому +5

    Really helpful, sir! Thank you! Have a test coming over this Wednesday, and I have a feeling that it will go well

  • @frostbite1061
    @frostbite1061 2 роки тому +1

    Found this right before my final, you're a life saver!

  • @MrCEO-jw1vm
    @MrCEO-jw1vm 7 місяців тому

    Thanks so much, Dr. Bazett! I can see the patterns to use to differentiate and evaluate these various series.

  • @SISKCERTWaJaVlogs
    @SISKCERTWaJaVlogs 2 роки тому

    This guy speaks very passionitly and its amazing keep up the amazing vids homie!

  • @rickynotplayin9930
    @rickynotplayin9930 4 роки тому +3

    you seem so proud of your progress and im over struggling and giving up

    • @hanbean22
      @hanbean22 4 місяці тому

      where r u now? i hope u survived it well :)

  • @syd5604
    @syd5604 Рік тому

    thank you!! it’s sooo hard to find concise videos like this

  • @ellen128
    @ellen128 3 роки тому +2

    Thank you for this really nice video, Dr. Bazett!! Thank you for going to the details of why you did what you did instead of just presenting the solutions!

  • @krizh289
    @krizh289 2 роки тому

    Haven't gone to any classes and now I'm cramming for the test today.

  • @akhildev312
    @akhildev312 3 роки тому +5

    I think in the divergence test example we can only conclude when the modulus series is convergent as when the modulus series is divergent then we cannot conclude that is because alternating series has alternating +, -. We have the case of conditionally convergent if sigma|un| is divergent and sigma un is convergent. So it is wrong to conclude if the modulus series is divergent

  • @DomenicC-e3u
    @DomenicC-e3u 9 годин тому

    I appreciate your enthusiasm.

  • @airdroper6960
    @airdroper6960 2 роки тому +2

    It's It's shame I only found you the day before my Calc 2 exam. Oh well, better late than never.

  • @nahommerk9493
    @nahommerk9493 Рік тому +1

    I am here with 30 min left for my exam and binge watching anything that can serve as a shortcut 😭😭. Wish me luck

  • @lammartial
    @lammartial 3 роки тому +2

    thank you, it really helps me prepare for my final exam !!

  • @yamsang0__0
    @yamsang0__0 Рік тому +1

    Very clear and instructive. Thank you

  • @sirenofamphitrite4612
    @sirenofamphitrite4612 6 місяців тому

    watching this before my calc 2 final, thanks for helping me cook

  • @biggerthaninfinity7604
    @biggerthaninfinity7604 3 роки тому +2

    I had trouble with determining what to use, so thank you so much for making this video!

  • @roaakanaan9459
    @roaakanaan9459 3 роки тому +1

    EXACTLY WHAT I NEEDED !!

  • @OHHS2
    @OHHS2 Рік тому

    Thanks from the bottom of my heart. You truly are a legend ❤️❤️❤️

  • @marypoppins6290
    @marypoppins6290 2 роки тому +1

    this video was a goldmine for me! Thanks a lot

  • @filipsperl
    @filipsperl Рік тому

    Forgot all about these test. I remember I had fun with them in university :)

  • @mauriciobenjaminmossi8231
    @mauriciobenjaminmossi8231 6 місяців тому +1

    For \Sigma sqrt(n^3+n)/(n^4-n^2) is the following a valid test for divergence / convergence: sqrt(n^3+n)/(n^4-n^2) < n^2/(n^4-n^2) < n^2/(n^2(n^2-1)) < 1/(n^2-1) < 1/n^2, and in the limit 1/n^2 tends to zero.

  • @alyssiatan
    @alyssiatan 2 роки тому +1

    got my ap exam today thank you🙏🏽

  • @becky7564
    @becky7564 4 роки тому +1

    Thanks for saving my math... this is really helpful!

  • @Vaishnav_._411
    @Vaishnav_._411 11 місяців тому

    Awesome experience of studying from your lectures✨.. really very helpful💫

  • @exploringcar12
    @exploringcar12 3 роки тому +2

    Seeing it from India...really nice ..

    • @exploringcar12
      @exploringcar12 3 роки тому +1

      Even I want to know from where are u sir..

  • @LisaLopez-pg2yz
    @LisaLopez-pg2yz Рік тому +1

    literally a life saver

  • @themysteriousfox3767
    @themysteriousfox3767 2 роки тому

    Never have I seen a man so excited about alternating series.

  • @A_Random_Ghost
    @A_Random_Ghost 2 роки тому +1

    Thank you for uploading this video. Helped a lot.

  • @vg4706
    @vg4706 3 роки тому +2

    Wow, awesome, just wanted this explanation 👏👏

    • @DrTrefor
      @DrTrefor  3 роки тому +1

      Glad to hear that!

  • @funkypanda5700
    @funkypanda5700 5 років тому +2

    Watching 1 day before exams thanks..

  • @georgerusu5427
    @georgerusu5427 Рік тому +1

    This video saved my life

  • @rob6129
    @rob6129 4 роки тому

    Great summary and quick practice problems for the methods!

  • @pauminguetmarti18
    @pauminguetmarti18 2 роки тому +1

    great video, super helpful and much clearer than my professor

  • @lakshminiharika4918
    @lakshminiharika4918 Рік тому

    I am here enjoying your communication skills 🥰

  • @fernanmontevista204
    @fernanmontevista204 3 роки тому +2

    Hey doc very nice presentation .Keep it up..From the philippines

  • @erasingtheuigours5560
    @erasingtheuigours5560 4 роки тому

    Fast and clear. Good job!!

  • @maximlavrenko1164
    @maximlavrenko1164 2 роки тому

    awesome, cool to have a refresher for all of the tests

  • @Natolino83
    @Natolino83 Рік тому

    You have a small problem in the 4th series of the left, see that can't evaluate the sequence at n =1, because of its denominator. I still love your videos. Congrats!!

  • @builtfromashes9447
    @builtfromashes9447 Місяць тому

    This is so helpful thank you!

  • @destitaaa
    @destitaaa 3 роки тому +1

    great explanation, thank you!!

  • @07rockzz92
    @07rockzz92 3 роки тому +1

    Truely amazing no words

  • @charbilysf7592
    @charbilysf7592 11 місяців тому +1

    Good work dr!!

  • @Waterburgers
    @Waterburgers 2 роки тому +1

    Thanks my dude!

  • @funnygirl6309
    @funnygirl6309 4 роки тому +1

    thank you sir so much you are the best of them allllll

  • @gayanivishara835
    @gayanivishara835 3 роки тому +1

    really helpful.Thank you

  • @muthukrishnann4505
    @muthukrishnann4505 5 років тому +2

    Fabulous work dear

  • @Lukaspecial599
    @Lukaspecial599 4 роки тому +11

    Im confused how where the n+1 went in the geometric series?

    • @donnaaardoom9261
      @donnaaardoom9261 3 роки тому +4

      1/25 = 5^-2 and 5^(n+1)/ 5^-2 = 5^(n-1)

    • @amoghus
      @amoghus 3 роки тому

      if bases are same then powers are added so we can subract one from the power of 5 to take a 5 as common and he did it twice

  • @fabianrivera9905
    @fabianrivera9905 7 місяців тому

    The quotient criteria also works for the exponential thing ❤😂

  • @faoizashraf1027
    @faoizashraf1027 4 роки тому

    bro you made cal soooooooo easy and interesting for us..... thanks a lot.......

  • @btbt2423
    @btbt2423 5 місяців тому +1

    Thank you !! You're a saver

  • @karl1x656
    @karl1x656 20 днів тому

    thank you my friend!

  • @trustkibou
    @trustkibou 3 роки тому +1

    I love you and I love this video - thank you

  • @samarneson9475
    @samarneson9475 3 роки тому +1

    So. Freaking. Helpful!

  • @grishproduction1243
    @grishproduction1243 3 роки тому

    You could also include Telescoping series

  • @aaronelharo5159
    @aaronelharo5159 5 років тому

    Amazing content man. Very clear and helpful.

  • @marcusmoulia639
    @marcusmoulia639 2 роки тому

    That was a great video. Love this

  • @nickdowney9003
    @nickdowney9003 2 роки тому +1

    wow this was super helpful

  • @SempatikBalkc
    @SempatikBalkc 4 місяці тому

    at 10.53 you missed the series should be positive obligation there is 3 condition to utilize AST should be decreasing must be bigger than zero and its limit should be zero

  • @vijayvarma5501
    @vijayvarma5501 4 місяці тому

    Sir at 3:50
    The series in the form summation [(-1)^n / sqrt(n)] but not in form of [ (-1)^n-1/sqrt(n)]
    To apply alternative series test.
    So you can also say by alternative test summation[ -1^n/sqrt(n)] = summation[(-1^n-1 )* -1 / sqrt(n)]
    Here bn= -1/sqrt ( n) so bn is negative and by alternative test it divergence
    Sir got confused there. But overall great explanation

    • @slimereeper
      @slimereeper Місяць тому

      No. It converges. Check again

  • @xavarchive
    @xavarchive Рік тому +1

    10:43 The limit as n approaches infinity of 1/sqrt(n) diverges not coverges. The series is a p-series with p = 1/2... a p series is divergent for all p < 1.

    • @vijayvarma5501
      @vijayvarma5501 4 місяці тому

      Yes you can also say by alternative test summation[ -1^n/sqrt(n)] = summation[(-1^n-1 )* -1 / sqrt(n)]
      Here bn= -1/sqrt (n) so bn is negative and by alternative test it divergence
      Sir got confused there. But overall great explanation

    • @sreya2004
      @sreya2004 2 місяці тому

      Dude, you can't use p series for an alternating series. It is clearly not of p series. If there is (-1)^n in question, then it is alternating series not p series coz p series is of form 1/n^p

  • @alexrosellverges8345
    @alexrosellverges8345 3 роки тому +1

    Really good video i loved it

  • @ajputk4639
    @ajputk4639 3 роки тому +1

    Well Done 😎

  • @schrodinger7230
    @schrodinger7230 Рік тому

    helped me a lot

  • @kellyh6359
    @kellyh6359 Рік тому +4

    How the heck do you get 1/25 for the second one?

  • @payeldutta7133
    @payeldutta7133 3 роки тому +1

    It worths the 12 minutes before exam 🙃

  • @jeffreynatividad1937
    @jeffreynatividad1937 4 роки тому

    So helpful Thanks a lot!!!

  • @f_46_raimabanerjee85
    @f_46_raimabanerjee85 Рік тому

    thanks u make infinite series finite for exams (3 days down)

  • @geetajina5304
    @geetajina5304 5 років тому

    Great video sir. Keep it up

  • @Tanya-py7gi
    @Tanya-py7gi 3 роки тому +2

    My exam is in 12 minutes😂 btw thank you it was helpful

    • @DrTrefor
      @DrTrefor  3 роки тому +3

      Good luck lol:D

    • @Tanya-py7gi
      @Tanya-py7gi 3 роки тому +1

      Thank u , my test went well😁

  • @ritouddin9915
    @ritouddin9915 4 роки тому +1

    if only i could prove the convergence like this and without any rigor lol

  • @Treabor314
    @Treabor314 Рік тому

    Somebody correct me if I'm wrong. The last one you have with the denominator = n^4-n^2 diverges because "a" sub 1 DNE. You would need to start n at 2 for that to converge.