Proof: 2^n is Greater than n^2

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  • Опубликовано: 11 янв 2025

Комментарии • 47

  • @antariowoods9545
    @antariowoods9545 3 года назад +31

    By far this is the best explanation to this problem I have ever seen. It takes patience but boy is it rewarding to finally understand it. thanks a lot! Subscribed
    (my final is tomorrow morning)

    • @WrathofMath
      @WrathofMath  3 года назад +3

      Thanks so much, Antario! I always try to craft the clearest explanations I can. I have many other proofs on my channel, induction and otherwise - do let me know if you ever have any specific requests (my lessons this month are Christmas-themed so they have some extra spice). Good luck on the final!

    • @jcn268
      @jcn268 10 месяцев назад

      No this was poorly explained lmao

  • @stoopidoo546
    @stoopidoo546 2 года назад +8

    My university course on mathematical methods for physics (maybe it's called that in english, maybe not) just begun and this was the first problem for us to prove in our homework. I've managed to get toward rewriting 2^(n+1) and solving the binomal on my own but due to never having been confronted with induction before, I quickly ran into troubles afterwards. Your video really helped me grasp this problem (massive thanks), tho I will definitely need a lot more practice to become comfortable with induction.

  • @Morejamsthanjimin
    @Morejamsthanjimin 2 года назад +6

    Thank you! I never understood when my prof explained induction, but with your explanation I understood immediately!

    • @WrathofMath
      @WrathofMath  2 года назад +1

      So glad to heat it, thanks for watching!

  • @nathanielcabansay4535
    @nathanielcabansay4535 3 месяца назад +1

    This is surprisingly useful for when you want to know why an algorithm with a time complexity of O(2^n) performs worse than one with a time complexity of O(n²)

  • @guilhermemonteiro446
    @guilhermemonteiro446 2 года назад +2

    The best explanation I found on youtube!

    • @WrathofMath
      @WrathofMath  2 года назад

      Glad to hear it, thanks for watching!

  • @benjaminvatovez8823
    @benjaminvatovez8823 3 месяца назад

    Thank you for this video! To people who are less intuitive or less experienced like me, I would suggest to do it this way for any k > 4 :
    First, 2^(k+1) = 2 . 2^k > 2 . k²
    and then 2k² > (k+1)² if and only if k²-2k-1 = (k-1)² - 2 > 0, which is true as (k-1)² - 2 > (4-1)² - 2 = 7 > 0

  • @z4_i
    @z4_i 3 месяца назад +1

    6:12 Why did you go 8 and write 1?

    • @WrathofMath
      @WrathofMath  3 месяца назад +1

      1) It's valid because +8 is greater than +1
      2) We made the change so that we could factor the expression into (k+1)^2

  • @ratmouse088
    @ratmouse088 2 года назад +3

    I agree that this has been the best explanation I've found. Finally get it!

  • @Mymath.
    @Mymath. 2 года назад

    Greetings from Turkey, this video's really useful thank you 🙏🏻

  • @shoopinc
    @shoopinc 3 года назад

    Thank you, great example of using the information about the integers of interest to run induction.

    • @WrathofMath
      @WrathofMath  3 года назад +1

      Thanks shoop! This is a classic!

  • @niha1398
    @niha1398 Год назад

    thank you so much for your efforts my youtube sir

  • @mymentalhealthjournal2610
    @mymentalhealthjournal2610 3 года назад +2

    Where did the 1 come from? Why did you suddenly say that 8 is greater than 1, why is it specifically 1? Or do we let it be specifically 1 because we want to make it become k^2+2k+1?

    • @WrathofMath
      @WrathofMath  3 года назад +2

      Thanks for watching, and exactly! Eight is greater than a lot of things, we only point out the one that's useful!

  • @concept-math
    @concept-math 8 месяцев назад

    question no. 32. .
    why we ignored that term.
    there should be some reason behind

  • @dyip-vb1wl
    @dyip-vb1wl 2 года назад +4

    where did you get the k^2 + 4k

    • @Sir_Isaac_Newton_
      @Sir_Isaac_Newton_ 9 месяцев назад +1

      Did you watch the video?
      2k² = k² + k² > k² + 4k
      And we know that last "greater than" is true because k > 4

    • @Debbs-h
      @Debbs-h 14 дней назад

      @@Sir_Isaac_Newton_ where did you exactly come up with the 4k afer having k.k part ?

  • @aleggs2813
    @aleggs2813 2 года назад +1

    wait so why do we ignore 0 and 1 and jump straight to n = 4? someone please explain. do we just ignore those for some reason?

    • @EliCrystal
      @EliCrystal Год назад

      because it isn’t true for any numbers less than or equal to 4. for example, with n=3, 2^3>3^2 is False.

  • @xartos299
    @xartos299 8 месяцев назад

    Thanks a lot🎉

  • @souhir1700
    @souhir1700 4 месяца назад

    Thank u so much nice explanation

  • @firstname4337
    @firstname4337 3 года назад +1

    this was a great explanation -- but my class wants it done by minimum counterexample (:

  • @jcn268
    @jcn268 10 месяцев назад +1

    3:31 is wrong you cant just double up both sides

    • @WrathofMath
      @WrathofMath  10 месяцев назад

      It’s correct, you can multiply both sides of an inequality by 2.

  • @anty.
    @anty. 11 месяцев назад

    where did the assumption of k*k being greater than 4k come from? like i get it has to do with k being greater than 4 but i don't know what mathematical rule this is. i'm a sophomore taking discrete math and i haven't done any math for over a year lol
    edit: nvm i get it, since the minimum of k is 5 then that means that k*k is equivalent to at least 5*5 rather than only 4*5

    • @sailor5853
      @sailor5853 6 месяцев назад

      You have k*k, and k > 4 so you can turn one of the k's into a 4 and have k*k > 4*k > 4*4

  • @BleniousNgambi
    @BleniousNgambi 9 месяцев назад

    Thanks alot

  • @gani999
    @gani999 3 месяца назад +1

    2^n is not greater than n^2 for n = 2 , 3 or 4.

    • @WrathofMath
      @WrathofMath  3 месяца назад

      that's why I specify n>4

  • @asaanimals1057
    @asaanimals1057 10 месяцев назад

    Thank ❤

  • @tariqmath1845
    @tariqmath1845 11 месяцев назад

    Thnx

  • @al8905
    @al8905 Год назад

    neat

  • @user-zy8kr2zy5s
    @user-zy8kr2zy5s 3 года назад

    Help me,
    What's length and width

  • @tapashgayen7237
    @tapashgayen7237 Год назад

    This is not tricky it's easy it come in our exam only 2 marks

    • @dyip-vb1wl
      @dyip-vb1wl Год назад +6

      Do you want a medal or smth 😂😂

  • @jakederouin9116
    @jakederouin9116 2 года назад

    o K