Ratio Test

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  • Опубліковано 29 бер 2018
  • This calculus 2 video tutorial provides a basic introduction into the ratio test. Examples include the ratio test with factorials, exponents, fractions, and square roots. If the limit of the ratio of next term with the previous is less than 1, the series converges. If it's more than 1, the series divergence. If the limit equals 1, the ratio test is inconclusive.
    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

КОМЕНТАРІ • 260

  • @TheOrganicChemistryTutor
    @TheOrganicChemistryTutor  Рік тому +8

    Next Video: ua-cam.com/video/ahf0eXOll1M/v-deo.html
    Final Exams and Video Playlists: www.video-tutor.net/

  • @edinh2601
    @edinh2601 7 місяців тому +33

    Wishing everyone a good Calc 2 final grade

  • @AyakaSori
    @AyakaSori 6 років тому +359

    SERIOUSLY keep doing what you’re doing. I just ACED the hardest Calc 2 Exam just based of your videos. Thank you so much for what you do. 💗

    • @ARTDEVGRU247
      @ARTDEVGRU247 Рік тому +5

      Belated congrats girl 👏 👏 👏

  • @angeloid_
    @angeloid_ 4 роки тому +87

    Of all the people who do calculus tutorial videos, yours are the most concise and the easiest to understand. Whenever I'm scratching my head over calculus, you always seem to have the answer. Thank you for being amazing

  • @tannerbarcelos6880
    @tannerbarcelos6880 4 роки тому +727

    Calc 2 wasn’t too bad till chapter 11 - series lmao

    • @dremr2038
      @dremr2038 3 роки тому +46

      What about integration??
      I hate it lol

    • @Mymelodyismy123
      @Mymelodyismy123 3 роки тому +102

      @@dremr2038 Integration is fun, just don't know how to do it though

    • @dremr2038
      @dremr2038 3 роки тому +54

      @@Mymelodyismy123 lol , yes it is fun if you know how to use the right substitution and if you have good teacher. 😅

    • @BossKing1243
      @BossKing1243 3 роки тому +19

      Idk I’m fking lovin series rn lol

    • @priscilladoran9545
      @priscilladoran9545 3 роки тому +31

      @@BossKing1243 SAME DUDE. I just hated the trigonometry section

  • @pinkroseeee
    @pinkroseeee 9 місяців тому +23

    To be able to passs this section for chapter 11 calc 2
    *know all the types of tests
    *know when is the test applicable
    *know the conditions of the test
    *familiarize yourself with some examples of each test from easy to challenging level
    Believe in yourself!❤

  • @justinjohn1308
    @justinjohn1308 4 роки тому +33

    You are the reason I pass my study man. Seriously. I don't know you. But you are a living legend.

  • @adam3141
    @adam3141 3 роки тому +38

    Just want to say a big thank you to The Organic Chemistry Tutor. I think this repetition style of learning is key in getting the concepts. I am learning Linear Algebra and Calculus at Uni (these are not even the advanced courses) and it is all abstract, dry and mainly focusing on definitions and theorems with very little examples.
    I think that maybe because the Lecturers know this kind of stuff back to front, they probably make it harder than they might realise. Some people might understand from abstract but I learn from concrete examples and I love examples where I can practice the method

  • @anthonywu1354
    @anthonywu1354 5 років тому +83

    These 'series' of videos (pun intended) saved my semester lmao

  • @imrgohard270
    @imrgohard270 5 років тому +305

    can you please take my final exam for me? I've been lost since my teacher said hi guys welcome to calc 2.

  • @blakkermambaa
    @blakkermambaa 5 років тому +9

    Thanks so much! I was looking for help all yesterday cause I wasn't getting factorials and I was having a rough time on this chapter. This is one of the more helpful videos I found. Summer classes suck! Definitely feel better about my test next week now.

  • @matthewnorris7118
    @matthewnorris7118 4 роки тому +73

    I wish I found this channel sooner than 3 hours before my exam

  • @varunraju1569
    @varunraju1569 4 роки тому +9

    What a wonderful set of examples! Thanks for this, great video!

  • @lburger404
    @lburger404 Рік тому +12

    These videos are 4 years old at this point but still very helpful! Thank you for showing all the steps!

  • @leoxu7826
    @leoxu7826 3 місяці тому +1

    SERIOUSLY keep doing what you’re doing. I just ACED the hardest Calc 2 Exam just based of your videos. Thank you so much for what you do.

  • @mathwithnour9780
    @mathwithnour9780 4 роки тому +9

    ماشاء الله عليك كون عدنة بالوطن العربي واحد مجتهد مثلك ... ❤️
    Your video is helping me thanks 🙏

  • @nozzerjuice
    @nozzerjuice 5 років тому +26

    these geometric series problems have me SHOOK.

  • @abeermohamed6960
    @abeermohamed6960 4 роки тому +11

    bro i passed calculus 1 and 2 because of you, thank you for real.

  • @georgesadler7830
    @georgesadler7830 2 роки тому +6

    Professor Organic Chemistry Tutor, thank you for another fantastic video/lecture on the classic Ratio Test in Calculus Two. This is not a difficult test to breakdown; however, the algebra could be problematic for all Calculus students. Algebra is important in all levels of Mathematics. This is an error free video/lecture on UA-cam TV with the Organic Chemistry Tutor.

  • @Lexyvil
    @Lexyvil 2 роки тому +3

    The factorial part was what always got me lost, glad to know there's a way to work with them.

  • @ExplosiveGuides
    @ExplosiveGuides 5 років тому +3

    Great video, as always.

  • @coleabrahams9331
    @coleabrahams9331 2 роки тому +2

    Absolutely phenomenal!

  • @wahidnoori2259
    @wahidnoori2259 5 років тому +3

    Very helpful, Thanks!

  • @Mohamed-dy7rx
    @Mohamed-dy7rx 4 роки тому +1

    Almost addicted your videos!!

  • @enockkipkoechcheruiyot3611
    @enockkipkoechcheruiyot3611 2 роки тому +1

    really greatful sir... you are father of calculas,,, God bless you

  • @tapiwamwila2437
    @tapiwamwila2437 5 років тому +4

    Thank yu so much finally got to understand ratio test💃

  • @yianwang8425
    @yianwang8425 2 роки тому +2

    We can take advantage of the two important limits to conclude that the limit is equivalent to e. The utilization of LH rule is relatively complex.

  • @srithummalapalli3333
    @srithummalapalli3333 2 роки тому +3

    got a test tomorrow wish me luck guys!

    • @Lovenyalenee
      @Lovenyalenee 2 роки тому +1

      Good luck you got this 😌✅

  • @brandybabyyy
    @brandybabyyy 4 роки тому +3

    can u explain why for the last qn, u absolute the eqn, (like when u remove the (-1)^n)

  • @Nicole-yq3lw
    @Nicole-yq3lw 5 років тому +5

    you're actually a god and thank you

  • @katkrasher
    @katkrasher 3 місяці тому

    Actually the best channel ever created

  • @biggerthaninfinity7604
    @biggerthaninfinity7604 3 роки тому +1

    Great video 👏🏼 👏🏼

  • @camileclere8925
    @camileclere8925 2 роки тому

    love your videos!

  • @yazenhammada7688
    @yazenhammada7688 6 років тому +4

    true hero indeed

  • @ahmedhadwan9273
    @ahmedhadwan9273 3 роки тому +1

    THANK YOU SO MUCH

  • @richie1603
    @richie1603 5 років тому +2

    Life saver for days

  • @brennabubblegum10
    @brennabubblegum10 5 років тому +12

    How do we solve the last problem? I am very sad that you cut the video short. What test should we use?? I love you btw and love your teaching methods! I have learned more from you than any professor I have taken these last couple semesters. YOU ARE AMAZING!!!!

    • @taimal-n2435
      @taimal-n2435 Рік тому +1

      direct comparison test with p-series 1/n^1/2

    • @unicorn3602
      @unicorn3602 3 місяці тому

      or you can do alternating series test

  • @ytpop7281
    @ytpop7281 3 роки тому

    Thank you very much sir...

  • @source_one9146
    @source_one9146 17 годин тому

    You deserve all my lectures' salaries

  • @engisasp4808
    @engisasp4808 3 роки тому

    Thank-you very much

  • @3z____
    @3z____ 5 років тому +13

    5:47 you could have just done L'hopital's Rule to save time :) Great video !

  • @jedidiahchibinga1537
    @jedidiahchibinga1537 3 роки тому

    9:52 would it be right to write it as ((n+1)/n)^2 ? so that we get (1+1/n)^2

  • @krayzeehprolly
    @krayzeehprolly Рік тому +1

    Calculus wasn't this easy until I found ur channel fr

  • @adam3141
    @adam3141 3 роки тому +2

    With the sum of 2^(4n+1) / n^n for n=1..inf
    I didn't get 16*(1/e)*0. Although I did still end up with 0
    In the intermediate steps, about 20:50 time index. I actually cancelled the n^n by noticing that (n+1)^(n+1) is just (n+1)*(n^n) so I was left with a 1/(n+1) in the denominator. Is this still a correct way of doing this?

    • @marcushendriksen8415
      @marcushendriksen8415 10 місяців тому +1

      No, because it's not true that (n+1)^(n+1) = (n+1)*(n^n). Take n=3 for example. 4^4 = 2^8 =256, but 4*(3^3) = 4*27 = 108. 256 is certainly not equal to 108, and only one counterexample is needed to disprove the notion

  • @Nick-zi4iq
    @Nick-zi4iq 4 роки тому +1

    What's the difference when this rule is used with a sequence?

  • @sarwarmohammed3769
    @sarwarmohammed3769 Рік тому +1

    as a this video is 5 yers ago but it still live saver god bless you man

  • @sam2026
    @sam2026 6 років тому +20

    Very good videos. Hope to get an A in calc. Have an 86. Need 100s on my series retest and my final for a shout.

  • @yungcashregister8587
    @yungcashregister8587 3 роки тому +3

    So for the last question that was inconclusive, would you have to find another test to prove if it converges/diverges?

    • @CPisco
      @CPisco 2 роки тому

      Another test maybe.

  • @aidilshahfiq2950
    @aidilshahfiq2950 5 років тому +3

    on 15:58, why we need to find derivative? is it to remove ln or is it the law?

    • @faisalsaddique3323
      @faisalsaddique3323 5 років тому +1

      if we directly put the limit, it becomes 0/0 form, which is indeterminate form. so we apply L'hopitals on both numerator and denominator

  • @Himawari_.
    @Himawari_. 5 років тому

    thank you

  • @jackpurcell7316
    @jackpurcell7316 2 місяці тому +1

    Just failed my pre calc exam😭 but this made it a lil better

  • @rohhanbhardwaj
    @rohhanbhardwaj 4 місяці тому

    can any tell how we know which test to use like where to use ratio test ,where to use AST or p series

  • @dezld4475
    @dezld4475 Рік тому

    Thanks again

  • @RaneemAhmad-sd5nr
    @RaneemAhmad-sd5nr Рік тому

    very nice video

  • @pistachio66
    @pistachio66 4 роки тому +2

    Is the limit as n goes to infinity of the absolute value of the quantity of (1 +1/n)^n equal to 1? Why did he have to go further than that? 14:23

    • @ytpop7281
      @ytpop7281 3 роки тому

      Because 1^infinity is an indeterminate form....don't you think this reminds of something from calculus...

  • @luigigeronimo5747
    @luigigeronimo5747 3 роки тому +2

    on 26:04, you divided the limit's numerator and denominator by 1/n, can someone explain how that happened?

    • @henri1_96
      @henri1_96 3 роки тому +1

      he wants to get rid of inf/inf situation. What he does is the same as forcing "n" as the common denominator like this: n(1+3/n)/n(1+2/n) .

  • @anonymousstormchaser
    @anonymousstormchaser 5 років тому +5

    Can someone explain why he's multiplying fraction by 1/n^2 at 10:24?

    • @farlok1000
      @farlok1000 5 років тому +6

      @AnonymousStormChaser He is simplifying the limit equation by dividing every term but the largest nth term so that when he takes the limit it should have lots of zeros (because lim n->infinity 1/n = 0). Could also use L'Hopital's rule but this avoids derivatives.

    • @OPP534
      @OPP534 3 роки тому

      that step in my opinion just complicates it. Since the magnitude of the numerator and denominator are both equal just use the common ration of the leading coeffiecnt

  • @gn18
    @gn18 5 років тому +1

    God bless you bruh!

  • @silversentai2402
    @silversentai2402 2 роки тому

    why do you just move stuff from one side of the fraction to the other?

  • @blankrealist8872
    @blankrealist8872 Рік тому

    Thanks

  • @steveamores5955
    @steveamores5955 4 роки тому +1

    If the problem just like the last one is inconclusive, will using other tests for convergence must be used?

    • @allenburt1475
      @allenburt1475 4 роки тому +2

      Steve Amores
      yeah then you need to use other tests

  • @koenabennedict6189
    @koenabennedict6189 6 років тому +2

    Thank you. This helped a lot. Didn't you omit a negative in the last question?

  • @OwO-_-UwU
    @OwO-_-UwU 4 роки тому +2

    Can someone please explain as to why the (-1)^n +1 just disappears and is not useful? 24:39

    • @ravistman1254
      @ravistman1254 4 роки тому

      The ratio test has you taking the abs. Value of the series which just negates the -1^n

  • @jessedossey1442
    @jessedossey1442 9 днів тому

    For the last problem, instead of multiplying both sides by 1/n, couldn't you just L'Hopital your way through? I'm getting the same answer that you got. Thanks

  • @afzaalali3796
    @afzaalali3796 3 роки тому

    Thank you sir g

  • @gabrielsilva1267
    @gabrielsilva1267 2 роки тому

    My teacher is good but you are just amazing

  • @Shaodanlllllun
    @Shaodanlllllun 3 місяці тому

    This part is really hard to understand, i need at least mins to solve each question when i try to do it by myself , I hate math but thank you so made this video to help me through those time

  • @KylianMbappe07303
    @KylianMbappe07303 5 місяців тому +1

    5:31 why did you swap the n and 4**(n+1)

  • @palesashandukani7325
    @palesashandukani7325 5 років тому +2

    how did u get 1/e

  • @marin9207
    @marin9207 4 роки тому +2

    can someone pelase explain why he multiplied by (-n^2) at 16:50? I thought it was supposed to be 1/n^2

    • @HailoiHailoi
      @HailoiHailoi 4 роки тому

      because -n^2 times 1/n^2 canceled each other which equal 1? if you do multiply by 1/n^2 it gonna be 1/n^4 which it doesn't cancel out!

  • @blacksand8427
    @blacksand8427 6 років тому +6

    Our savior

  • @ryanhessong8460
    @ryanhessong8460 5 років тому +18

    thank you Mark Wahlberg

  • @yeny7194
    @yeny7194 5 років тому

    how did he get n! in the left denominator?

  • @user-el9xx3xj8n
    @user-el9xx3xj8n 9 місяців тому

    if we take the abs value of our ratio and L < 1, won’t our series ABSOLUTELY converge (hence also converge)? Is this correct to imply?

    • @Peter_1986
      @Peter_1986 7 місяців тому

      Yes, the Ratio Test checks for absolute convergence;
      you can also sort of use it as a Divergence Test, since L > 1 will tell you that a series diverges.
      The Ratio Test is a very powerful test.

  • @milesweckerle
    @milesweckerle 2 роки тому

    Precalc will be the death of me, but you might've prolonged it slightly. I thank you for that.

  • @abufazalansari3074
    @abufazalansari3074 3 роки тому

    How to chek for it?
    (3^n+n^2)/(6^n+8^n)

  • @jamessieglock946
    @jamessieglock946 4 роки тому +3

    UA-cam no longer supports the skip button for ads.

  • @isaaaac1223
    @isaaaac1223 4 роки тому +1

    Hey can you explain how (n+1)! is the same as (n+1)n!?

    • @breeromero7668
      @breeromero7668 4 роки тому +1

      (n+1) n (n-1)(n-2)(n-3), the n! implies you are decreasing
      ex. IF n+1=5 then our n is 4 so (n+1=5) 4 (4-1=3) (4-2=2) (4-3=1) notice its 5,4,3,2,1 going down in value

  • @rashmikababajee3328
    @rashmikababajee3328 6 років тому +4

    at 6:16 , you said that you will multiply the top and bottom by 1/n... but WHYYY :s ???

    • @SuperG3FR
      @SuperG3FR 6 років тому +2

      Rashmika Babajee he just took commen denameter

    • @ryanraymond321
      @ryanraymond321 6 років тому +3

      Rashmika Babajee if he solved for L by plugging in ∞ for x as it was, he'd have gotten ∞/∞ which isn't helpful, so a trick to get around this is to divide each term in the problem by the highest degree of the variable which when simplified allows L to be solved for as a finite number.

    • @manojkumar-nc2vz
      @manojkumar-nc2vz 6 років тому

      Rashmika Babajee hi

    • @raichu56k
      @raichu56k 5 років тому

      @@ryanraymond321 couldnt u just use l'hopital's rule though ?

    • @M15299
      @M15299 5 років тому

      @@raichu56k yes

  • @spacerocks9740
    @spacerocks9740 2 роки тому

    i wonder why dont you use L.H rule there to solve the limit isn't it simpler or I am wrong i guess

  • @muadzazri752
    @muadzazri752 4 роки тому

    Why ln y =1? If you differentiate the right hand side, shouldn't you also differentiate ln y too ? That is to say... 1/y = 1

  • @aizulamzar9744
    @aizulamzar9744 4 роки тому

    where can i get the video on how to +1 for the factorial?

    • @citizencj3389
      @citizencj3389 2 роки тому

      That's done to just cancel the n!. Remember n! = n x (n+1) x (n+2).....so (n+1)! = (n+1) x n!

  • @aicsynthesizer
    @aicsynthesizer 4 місяці тому

    how can we set the limit equal to y?????

  • @nicholasmaloof8378
    @nicholasmaloof8378 4 роки тому +5

    23:16 How is he getting 1/e? Whenever I work it out, I just get e.

    • @OwO-_-UwU
      @OwO-_-UwU 4 роки тому +5

      When you multiply by the -n^2 you should end up with ln y = -1, so y = e^-1. This can be re-written as y = 1/e. Hope that helps!

    • @long8398
      @long8398 4 роки тому

      Thats because the ^n is outside of your absolute value. Just simplify it and you get 1^n/((1+1/n)^n)

    • @akshayshende8201
      @akshayshende8201 3 роки тому

      @Hongki how he take n outside the modulus ? Please reply.

  • @faye638
    @faye638 5 років тому +1

    How could I solve the last example?

    • @firepup9924
      @firepup9924 5 років тому +1

      I am guessing divergence test

  • @Riotmaker55
    @Riotmaker55 5 років тому +5

    Sounds like a tire Mark Wahlberg which is great😂

  • @themansans1929
    @themansans1929 5 років тому

    12:57 why is it that you could just put the n! there? i am not very familiar with factorials but that seemed like it should change the problem

    • @farlok1000
      @farlok1000 5 років тому +2

      @Michael DeGrave Think of 4! which is 4*3*2*1 which is also equal to (4)*3! this is the same in this case, (n+1)! is (n+1)*(n)*(n-1)*(n-2)... which is the same as (n+1)*n!

    • @brianbc4
      @brianbc4 4 роки тому

      @@farlok1000 thanks for the explanation!

  • @adamnoel3936
    @adamnoel3936 5 років тому

    Are you from Boston?

  • @stevendorath7268
    @stevendorath7268 4 місяці тому

    This Root test is wild. And I thought I was good at calculus

    • @ENG.bishoLIOmessi
      @ENG.bishoLIOmessi 4 місяці тому

      Bro why last problem L≠-1 and it was = 1 , i think when dividing (-1) power (n+2) by (-1) power ( n+1) the result is -1 so L=-1 ... He ignored -1 absolutely!!!

  • @enockkipkoechcheruiyot3611
    @enockkipkoechcheruiyot3611 2 роки тому +1

    i did not understand why (-1)^n is not important sir. Can you explain more on that?

    • @sushi9521
      @sushi9521 2 роки тому +1

      24:00 This is 4 months later, so you probably know this alr, so ig this for the future calculus
      nerds.
      the (-1)^n or (-1)^n+1 only alternates the series from positive to negative. (-1, +1, -1 etc. for (-1)^n) and (1, -1, +1 etc. for (-1)^n+1). But this is not matter when doing the ratio test because the absolute value is taken which makes (-1)^n and (-1)^n+1 always equal to positive 1. If you multiply something by 1 you get the same thing so it is irrelevant in this case. hope that helps gl u peopel. :)

    • @enockkipkoechcheruiyot3611
      @enockkipkoechcheruiyot3611 2 роки тому +1

      @@sushi9521 thanks

  • @eggxecution
    @eggxecution 5 років тому +1

    12:58
    Help I got confused at this part. Where did the "n !" appeared at the denominator, where did it come from? Pls I really need to know.

    • @mdfaizanansari9567
      @mdfaizanansari9567 5 років тому +3

      its by opening (n+1)! into (n+1)n!
      its a basic concept. you can find it on google if you didnt get .

  • @joshuatamer1933
    @joshuatamer1933 4 роки тому +1

    Are you allowed to assume L'hopitals rule in Calculus?

    • @biggerthaninfinity7604
      @biggerthaninfinity7604 3 роки тому

      Thats what I do and still get the right answers, but you are not supposed to do that. So I’m just confused why it works.

  • @clairedo7735
    @clairedo7735 5 років тому +3

    Why is (n+1)! = to (n+1)n! ?

    • @nellvincervantes3223
      @nellvincervantes3223 5 років тому +2

      Example let n = 4
      Therefore
      (4+1)! = (4+1)(4!)
      5! = 5(4!)
      5x4x3x2x1 = 5(4x3x2x1)
      120 = 120

    • @MikeTheGreatCC12
      @MikeTheGreatCC12 4 роки тому +1

      @@nellvincervantes3223 3:03 How did he make 3^n+1 become 3^n * 3?

  • @jiro9081
    @jiro9081 2 роки тому +3

    ratio

  • @k12becgr62
    @k12becgr62 Рік тому

    Perfect presentation! what program is used for the presentation? Can we avail it?

  • @sibtainhaider2411
    @sibtainhaider2411 2 місяці тому

    11:07 if we don't simplify to this point, then the answer is 0. Because of 1/(infinity)2

  • @iltitty
    @iltitty 5 років тому +2

    1:14 the test is inconclusive, not the series.

  • @talithabemu2383
    @talithabemu2383 2 роки тому +1

    This comment is irrelevant but I think I'm falling in love with your voice.😂

  • @BKKGarrett
    @BKKGarrett 4 місяці тому

    These become much easier if you just memorize that the limit as n goes to infinity of [ (n+1) / n ] ^ n = e

  • @imidaraedo-ukpong711
    @imidaraedo-ukpong711 3 роки тому

    the last example is confusing because when you simplify at first you should have -1. therefore -1+1=0