how to easily write the epsilon-delta proofs for limits

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  • Опубликовано: 23 июл 2024
  • This calculus tutorial shows 2 examples of using the epsilon-delta definition to prove limits! Writing the epsilon-delta proof for a limit is usually considered to be the hardest topic when you first start learning calculus, especially at a college or university level. Hope this video gives you a better insight and my 4-step blueprint gives you a better guide to writing a beautiful math proof. Understand the epsilon-delta definition: 👉 • epsilon-delta definiti...
    more examples
    linear, square root, and quadratic 👉 • limits with epsilon-de...
    1/x and x^3 👉 • limits with epsilon-de...
    Start the epsilon-delta proof by writing
    1. given
    2. choose
    3. suppose
    4. check
    0:00 this could be your GPA saver
    0:10 ex1, linear function limit
    3:09 ex2, sqrt function limit
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Комментарии • 462

  • @blackpenredpen
    @blackpenredpen  Год назад +11

    The ultimate introduction to the εδ definition ruclips.net/video/DdtEQk_DHQs/видео.html

  • @serenitymayfair623
    @serenitymayfair623 2 года назад +297

    This taught me delta epsilon proofs better in 15 minutes than anyone else ever could in 10 hours of lectures

    • @richerram1
      @richerram1 2 года назад +10

      Same here. Although I get the aversion to "easy step by step formulas" of some teachers I think some things are better taught with some sort of "fixed procedure" until you start getting the handle of it... great lesson.

    • @Redeemed_Daughter
      @Redeemed_Daughter 2 года назад +2

      Tell me about it. I've been struggling for so long😅😅

    • @shivrajpatil1770
      @shivrajpatil1770 Год назад +1

      You mean 8 minutes and 27 seconds.

    • @kayceestudios6234
      @kayceestudios6234 Год назад +1

      @@Redeemed_Daughter yeah,I learnt the thing in just an 8 minutes video just imagine after wasting hours streaming useless videos that won't even explain what they are doing and why they are doing it

  • @Denis-vj2hz
    @Denis-vj2hz 3 года назад +195

    I'm a simple man. If π≈3 and e≈3 then π≈e. Done ✅

    • @pyyrr
      @pyyrr 3 года назад +73

      Hey look, it's an engineer!!

    • @El_Dr_Tacco
      @El_Dr_Tacco 3 года назад +2

      Ha ha ha true but it'works, that's why you got an iphone in your hands.

    • @BiscuitZombies
      @BiscuitZombies 3 года назад +1

      By pseudo-transitivity.

    • @akshatvats7992
      @akshatvats7992 3 года назад

      If it's close enough, it's good enough

    • @chill4r585
      @chill4r585 Месяц назад

      does anyone know why in the beginning we have to say "Given epsilon > 0" but not "delta > 0".
      Why cant we just "0 < |f(x)-L| < epsilon" just like delta?

  • @martinpena7949
    @martinpena7949 3 года назад +235

    *In the one hour exam*
    "Oh I'm not sure about this limit, let me prove it"

  • @divishthamalik309
    @divishthamalik309 3 года назад +18

    I have followed you through my high school and now I am still relying on your videos in my first year of engineering you have amazing content keep up the good work.Thanks a lot Sir.

  • @einsteingonzalez4336
    @einsteingonzalez4336 3 года назад +165

    "GPA saver"...
    More like career saver. It's necessary.

    • @blackpenredpen
      @blackpenredpen  3 года назад +16

      Definitely!

    • @benextinction__144
      @benextinction__144 3 года назад +7

      I thought you were me for a second and I was going loopy watching videos I'd already seen. Never seen anyone else with a map of CMB radiation as a profile pic. :)

  • @tzonic8655
    @tzonic8655 3 года назад +65

    I really had a hard time with epsilon-delta in my first semester in engineering but it turns out it's just matter of practice(for linear and 2nd degree polynomials 😅). It would be great if BPRP could show us geometrically the epsilon Delta

  • @osuh4947
    @osuh4947 2 года назад +15

    Wow, this really is the single greatest video about Epsilon-Delta proofs.
    I have never seen some one explain this as detailed and well as this guy.

    • @schezum
      @schezum 2 года назад +2

      I agree. This is the only video that enlightened me with this shit.

  • @SergeantTeabag
    @SergeantTeabag 2 года назад +9

    Extremely concise, thoughtful, and thorough explanation of how to use the epsilon-delta definition effectively and smoothly. This was so much more help than the book I'm reading through for Calculus. Thank you so much! This is a life-saver for college-level Calculus.

  • @hybmnzz2658
    @hybmnzz2658 3 года назад +322

    For the second last line in the last problem you should not write
    = 8 * epsilon/8
    but instead

    • @blackpenredpen
      @blackpenredpen  3 года назад +155

      Yes, I think you are correct.
      Thanks. Let me pin this comment so that others can see it. Thank you.

    • @daray21
      @daray21 3 года назад +35

      thank you filthy frank

    • @patriciaelenabarrosoberroc8032
      @patriciaelenabarrosoberroc8032 3 года назад +1

      Yes

    • @Cannongabang
      @Cannongabang 3 года назад +5

      But you might also set ε < 8 so you are sure that what BPRP wrote is clear.
      ( ͡° ͜ʖ ͡°)
      Also this is a joke, but still this would be without loss of generality (the statement for limits works ∀ε>0 if and only if it works ∀ε/ 0

    • @hybmnzz2658
      @hybmnzz2658 3 года назад +7

      @@Cannongabang yeah its a very tiny tweak. The full power of the epsilon delta definition is when epsilon is small anyway.

  • @blackpenredpen
    @blackpenredpen  2 года назад +12

    more examples:
    linear, square root, and quadratic 👉 ruclips.net/video/yC8Y50H6kw8/видео.html
    1/x and x^3 👉 ruclips.net/video/7VSG9G6EXrU/видео.html

    • @dunemeister5718
      @dunemeister5718 2 года назад

      where did you get your shirt from????

    • @mikevaldez7684
      @mikevaldez7684 Год назад +1

      Shouldn't delta be smaller than epsilon? Such as Delta = e/3 ?

  • @Rachel-tu8pq
    @Rachel-tu8pq Год назад +3

    exactly what I needed to help me in calc. love the way you can explain this dreaded topic so simply and have it be so effective!

  • @kennethgibson288
    @kennethgibson288 3 года назад +56

    This brings back so many memories!

  • @caghey
    @caghey Год назад

    i was reading a calculus book and i didn't understand a thing about this part but you made everything clear in 8 minutes! thank you so much!!!

  • @user-lt5wt9sv4j
    @user-lt5wt9sv4j 5 месяцев назад +2

    this might be the most useful video i've ever seen. somehow managed to gaslight me into thinking it was easy and simple and then it really became easy and simple thank you you are a magician

  • @harisl5994
    @harisl5994 2 года назад +1

    This man just explained the hardest topic in limits in just 15 Mins. Hats Off!!

  • @mohamedibrahim1023
    @mohamedibrahim1023 3 года назад +29

    Best professor of all time♥️🔝

  • @iwonthide
    @iwonthide 3 года назад +3

    was waiting for this video thanks man ❤️

  • @flyingcola7616
    @flyingcola7616 3 года назад +31

    I've never seen a simpler walkthrough for this! Thank you so much! Calc AB final is coming up in a couple of days

  • @smackdashitoutchu7755
    @smackdashitoutchu7755 2 года назад

    Wouldnt have been ever able to grasp this concept otherwise without this video. Thanks.

  • @frostinfy169
    @frostinfy169 3 года назад +3

    I've never been thought this method. I'll try to practice with it!

  • @UnevenerGgc2
    @UnevenerGgc2 3 года назад +1

    I’m not taking calc(not old enough yet to take it lol) but it was always difficult for me to wrap my head around quadratic epsilon delta proofs, it feels like this opened my 3rd eye

  • @ikersanchez8222
    @ikersanchez8222 3 года назад +3

    I wish I had found this video during my first college year. It is so well explained!

  • @chrisxd146
    @chrisxd146 3 года назад +6

    I almost wish my university would've had more time to focus on the delta-epsilon proof. We never went over the notation used for the limit of the quadratic so thankfully I learned about it before moving on from being an undergrad.

  • @adityakulkarni9230
    @adityakulkarni9230 3 года назад +9

    Learned something new. This was a bit different from other vids as I could try the problems along with you. Really a great experience.
    Please do keep having more such alongside trial videos.
    BPRP Yay!

  • @kr4301
    @kr4301 3 года назад

    I wish I had these videos back in times i was taking calculus I class. However I succeed my Calculus I part 2 exam (mostly based on series and series of functions) thanks to your videos

  • @jaloliddinzukhriddinov5820
    @jaloliddinzukhriddinov5820 2 года назад +1

    Thanks so much, you helped me to understand easily and fully about limits with epsilon, delta, thanks so much for your videos

  • @_AmitabhShukla
    @_AmitabhShukla 2 года назад

    DAMN! you explained it to me in just 15 minutes and I was struggling with it for last 2 hours . ......Thanks , man.

  • @AJ69238
    @AJ69238 2 года назад

    Excellent explanation! You're a life saver, man!

  • @hb1318
    @hb1318 Год назад

    You're a lifesaver. Thank you!

  • @shawnpcyril4200
    @shawnpcyril4200 2 года назад +3

    Every Math professor should be simple, clear and paced as you are. Thanks a ton !

  • @MichaelDuder
    @MichaelDuder 2 года назад +1

    Thank you so much for this... I am trying to get a headstart on calc out of Stewarts Calculus and they really don't do a very good job of explaining in the text so you just got me dug out of a ditch trying to understand what to do with exponents.

  • @2manynathans
    @2manynathans Год назад +1

    excellent video! It was the one that finally made it make sense!!!!!!!

  • @cellothere5723
    @cellothere5723 Год назад +1

    This is an amazing video, thank you so much!!

  • @ahadkhan7290
    @ahadkhan7290 3 года назад

    great explanation, made a complicated topic seem easy and simple!

  • @user-pj9ez4xp4r
    @user-pj9ez4xp4r 9 месяцев назад +1

    this dude's actually the best i can't even put it into words how grateful i am for him and his wonderful content!!

  • @BiscuitZombies
    @BiscuitZombies 3 года назад +1

    Thanks. I'm not in university yet, but I do like calculus and I think this is important.

  • @amyholmes8373
    @amyholmes8373 2 года назад

    Better explanation than the lecturers at uni, tysm!

  • @rishikagudlavalleti5241
    @rishikagudlavalleti5241 3 года назад +1

    This was so helpful thank you 😁😁🙏🙏

  • @ayberkkarakas6898
    @ayberkkarakas6898 2 года назад +1

    You're awesome mate!

  • @valsnemakonde6936
    @valsnemakonde6936 3 года назад

    Thank you so much, i should have known this channel before

  • @Nikolaij02
    @Nikolaij02 2 года назад

    thank you this is exactly what i needed

  • @Redeemed_Daughter
    @Redeemed_Daughter 2 года назад

    You are the best man🥺🥺 thankyou

  • @dognip
    @dognip 3 года назад

    I've just started calculus. It's nice

  • @thiwankapathirana9532
    @thiwankapathirana9532 Год назад +1

    Thank you so much for your help sir.

  • @ludwigfredriksson3786
    @ludwigfredriksson3786 3 года назад

    Thanks, you explained it much better than my professor. It clicked!!

  • @isaklyon7660
    @isaklyon7660 2 года назад

    thank you bro you explained better than my lecture did in 2hrs

  • @raghadsan603
    @raghadsan603 2 года назад

    that was so clear thanks

  • @foudilbenouci482
    @foudilbenouci482 Год назад +1

    Thank you very much you explaination is very efficient

  • @mr.jennycano1701
    @mr.jennycano1701 3 года назад

    very nice presentation. Thanks man!

  • @dansantner
    @dansantner 6 месяцев назад

    This is the best explanation I've ever seen. Every other Real Analysis lecture makes this way too difficult and confusing.

  • @advaitlath7221
    @advaitlath7221 3 года назад

    Hey man, love your videos. If you have time, could you please make a video series on the basics of linear algebra and calculus for beginners like me? Would be appreciated, as it's hard to come across quality content for beginners to grasp.

  • @jeremypolancolara2154
    @jeremypolancolara2154 2 года назад

    Nice explanation, very clear

  • @anikbhowmick1044
    @anikbhowmick1044 3 года назад

    Please make same type of video on two variable limits also . I am going through limits of two variables in my college but mostly sticking on proving the limit through epsilon delta definition

  • @LaBonneVentree
    @LaBonneVentree 2 года назад

    what a great video thanks for what you do on your channel

  • @muhammadmuaaz3704
    @muhammadmuaaz3704 2 года назад

    Bro you are nothing less than a life saver man thanks a lot bruh this video is amazing. .

  • @MrDZ-xc9ip
    @MrDZ-xc9ip 2 года назад

    Thanks teacher
    You save my life

  • @Mrsidd328
    @Mrsidd328 3 года назад +37

    I swear I heard him say "Idiot" at 2:28 (I know he says "in the end" but it confused me for a minute)

    • @przemezio
      @przemezio 3 года назад +3

      It sounds like "in D yet" :)

    • @valsnemakonde6936
      @valsnemakonde6936 3 года назад

      live lol

    • @navaerick86
      @navaerick86 3 года назад

      I felt like he was speaking directly to me.

    • @j.6230
      @j.6230 2 года назад

      @@navaerick86 To me as well, and he's right

  • @w7lves
    @w7lves 2 года назад

    this is kind of on me for not attending class after convo, but this man probably just saved me

  • @ShermukhammadKarimov
    @ShermukhammadKarimov 2 месяца назад

    thanks for clear explanation

  • @Ommbye
    @Ommbye 3 года назад

    Thank you is wonderful.

  • @Engineering_conceptsUOM
    @Engineering_conceptsUOM 2 года назад +1

    Excellent … thank you so much sir…

  • @AnmolWanderer
    @AnmolWanderer 2 года назад

    Amazing . Thanks !

  • @Bayesic
    @Bayesic 3 года назад +11

    Where was this kind of content when I was in calc 1? Amazing video man!

    • @aliaziz1145
      @aliaziz1145 3 года назад

      This isn’t in calc 1 b/c u don’t focus on proofs in that course. This content comes up in advanced courses

    • @Bayesic
      @Bayesic 3 года назад +3

      @@aliaziz1145 we definitely had a couple sections in my calc 1 class that were dedicated to delta epsilon proofs. Technically optional but not as far as my teacher was concerned haha

    • @aliaziz1145
      @aliaziz1145 3 года назад +1

      @@Bayesic this definition of a limit is so much more satisfying than the lower level sanitized definition from freshman year college 😂

  • @selamkibrom5618
    @selamkibrom5618 9 месяцев назад

    Owww thanks it helped a lot

  • @younesyounes3503
    @younesyounes3503 2 года назад

    Thanks, I understand this well

  • @fernandogaray1681
    @fernandogaray1681 3 года назад

    This video comes to me 1 year later 😭 still awesome for the new people :)

  • @medhanitgetachew1706
    @medhanitgetachew1706 3 года назад

    Tnxs you are a savior it was fun 👍👍

  • @147TINO147
    @147TINO147 3 года назад

    Very Nice, thanks a lot!

  • @paulnelson112
    @paulnelson112 3 года назад

    Awesome video, u know real numbers so good 👌👌

  • @MaadEngineer
    @MaadEngineer 11 месяцев назад

    many thanks! 💌

  • @mikoajmackowiak6993
    @mikoajmackowiak6993 3 года назад +1

    Even tho, I don't need this at school now, cool video.

  • @SuperYoonHo
    @SuperYoonHo Год назад +1

    THANK YOU!

  • @insectus4759
    @insectus4759 3 года назад +1

    Hello, thank you for this video, it is really helpful.
    I have a question in mind: In a new video, can you use the same method for the trigonometric and exponantial functions as well as a polynomial function which we cannot write as product of two or more polynomials? For instance as lim x->10 (x^2 -x+89). Because in the example showed in video, we reached x-2 easily so our assumption about delta was helpful. How are we going to do when it won't be like this?
    Thank you in advance and thank you for this amazing channel! Videos are not only helpful but also inspirational!

  • @danieltreuherz8752
    @danieltreuherz8752 3 года назад

    @blackpenredpen could i just square the limit in the second one to get rid of the square root? i got delta = epsilon/2 thanks!

  • @dakshthawani6704
    @dakshthawani6704 2 года назад +2

    it was really helpful, thanks a lot

  • @shivrajpatil1770
    @shivrajpatil1770 Год назад

    The last sentence of "We Are Done." is too satisfying!!!

  • @chileshesikazwe8500
    @chileshesikazwe8500 3 года назад

    thank you from Zambia

  • @nadhirelhaouari5659
    @nadhirelhaouari5659 2 года назад

    Thank you so much sir

  • @arunasadeepa2795
    @arunasadeepa2795 3 года назад

    That's a nice way😀 thanks

  • @therandomvidguy5141
    @therandomvidguy5141 3 года назад

    can you please love this for no reason

  • @linkoffate
    @linkoffate 3 года назад +4

    This guy is evolving to Master Xehanort

  • @darkwing73
    @darkwing73 3 года назад

    How do you formally prove this using the delta epsilon definition? Also, in the second problem, I got E^2/2-4E

  • @morongoakgarebe2574
    @morongoakgarebe2574 3 года назад

    Thank you man

  • @tharinduprabhath3377
    @tharinduprabhath3377 2 года назад

    Dude I was so fucked up by delta and Epsilon... You just solved it under 15 min.. Cool man.. You are a really good teacher.. Good Luck ❤️❤️❤️

  • @technicalbrains7675
    @technicalbrains7675 3 года назад +3

    That Pokeball looks awesome 😁

  • @joeyrunnion8042
    @joeyrunnion8042 2 года назад

    Thank you!

  • @songhiengvan
    @songhiengvan 3 года назад

    Thank you lifesaver

  • @user-qj3rv2mo1b
    @user-qj3rv2mo1b 9 месяцев назад +1

    Enjoyed it, explained with clarity, thank u, I will look for similar examples on YT from you to be able to solve all problem of this nature.

    • @blackpenredpen
      @blackpenredpen  9 месяцев назад

      Glad it was helpful! This is the video
      24 rigorous limit proofs (ultimate calculus tutorial)
      ruclips.net/video/AfrnYS5S8VE/видео.html

  • @charlesrothauser1328
    @charlesrothauser1328 3 года назад

    Nice - I wish I had you for my calc 1 professor. :-)

  • @shadrach05
    @shadrach05 10 месяцев назад

    Thank you so much

  • @alexandreclemson9445
    @alexandreclemson9445 3 года назад

    Thx thx really thx it took me several years to understand that damnned e-d stuff until I see your video.

  • @alibinfaizan8718
    @alibinfaizan8718 3 года назад

    Verry helpful.

  • @kayceestudios6234
    @kayceestudios6234 Год назад

    Thanks alot🙇

  • @firenzetanke2272
    @firenzetanke2272 2 года назад

    This is so much more understandable than how my professor explained it to me

  • @natnaelh.baraki2869
    @natnaelh.baraki2869 3 года назад +2

    What about for the cases when X approaches to infinity?🙏🏽

  • @kritikdutta6112
    @kritikdutta6112 3 года назад

    Thnx for this vid❤️

  • @ElemenTalParkour
    @ElemenTalParkour 2 года назад +1

    great explamation!!! do you have some examples with x going to infinity ?

  • @aidenhastings6341
    @aidenhastings6341 2 года назад +4

    Thank you! Do you have explanations of delta epsilon proofs in other contexts than just a limit (such as limit of a sequence, uniform continuity, etc)?

    • @blackpenredpen
      @blackpenredpen  2 года назад +2

      ruclips.net/video/2xmKUBgWk78/видео.html

  • @ninjapirate123
    @ninjapirate123 3 месяца назад

    This dude is a legend