Prove n! = O(n^n)

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  • Опубліковано 18 гру 2016
  • Prove by induction n factorial (n!) is Big Oh of n to the power of n O(n^n).
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КОМЕНТАРІ • 60

  • @cerealkiller1058
    @cerealkiller1058 Рік тому +3

    you deserve the world

  • @pilocchii
    @pilocchii 7 років тому +11

    My professor did this proof in class, but induction is kinda hard for me in general. Thanks for breaking it down and posting.

    • @randerson112358
      @randerson112358  7 років тому +4

      Yes, I too was very weak in using the induction method to prove things, you will get better over time the more you use it though !
      Thanks for watching ;
      randerson112358

  • @prateekthakur2519
    @prateekthakur2519 2 роки тому +1

    I think there should be some correction :-
    (k+1)! (k+1)! n! = o(n^n) instead of n! = O(n^n) (i.e. not tightest upper bound)

  • @d3struction61
    @d3struction61 7 років тому +5

    Well done. Very informative and helpful.
    Thank you and Great job!

  • @ekanshmishra4517
    @ekanshmishra4517 3 роки тому +3

    God bless you man!!! I was facing problem in doing that but your video is like angel from heaven.. thank you man💛

  • @bern1223
    @bern1223 3 роки тому +1

    Thank you for the video, I learned some new techniques!

  • @Doubleagentaron
    @Doubleagentaron 4 роки тому +2

    Why can (k+1)k^k < (k+1)(k+1)^k just be written as (k+1)^(k+1)

  • @faridashaikh9773
    @faridashaikh9773 3 роки тому +2

    Very neat explanation !! Thank you so much!! appreciate your contribution.

  • @ritubanerjee5061
    @ritubanerjee5061 5 років тому +1

    Thanks a lot for making it so easy to understand!!!

    • @randerson112358
      @randerson112358  5 років тому +1

      Wow, that is surprising ! Thanks for the nice comment, and I am glad this video helped you to understand how to do this.
      -randerson112358

  • @adrishbhattacharya508
    @adrishbhattacharya508 2 роки тому

    Thanks a lot sir..failed to ans this at an exm..Undrstood the concept now.. Thanks

  • @ryanhull2472
    @ryanhull2472 4 роки тому +1

    Wonder how he got rid of the k on the left side in going from
    =>(k+1)k! (k+1)!

    • @joelritter1336
      @joelritter1336 4 роки тому

      (k+1)k! is equivalent to (k+1)! by definition. (k+1)! is (k+1)(k)(k-1)... while (k+1)k! is (k+1)[k(k-1)...] so by the associative property they must be equivalent.

  • @carissabarrett2467
    @carissabarrett2467 5 років тому +5

    THANK YOU. THANK YOU. THANK YOU!

  • @juancaniza6069
    @juancaniza6069 7 років тому +1

    Thank you very much. Great job.

  • @gabor6259
    @gabor6259 6 років тому

    But how do we know that n^n is the smallest upper bound?

  • @user-zh4wr9mn8u
    @user-zh4wr9mn8u 6 років тому +2

    Very helpful, thank you!!!!

    • @randerson112358
      @randerson112358  6 років тому

      I am glad the video helped and thanks for watching!

  • @ifadaemmanuel5040
    @ifadaemmanuel5040 Рік тому

    Thanks for the helpful prove. Please using this, can anyone help on how I could prove n^100 (to the power of 100) is Big Oh of n! (factorial)?

  • @Tubeswax
    @Tubeswax 2 роки тому

    Why did you multiply (k+1) in both sides?

  • @wozhendeaa
    @wozhendeaa 4 роки тому

    5:45 where did the k^k come from?

  • @VenkatsundharSpBEC
    @VenkatsundharSpBEC 2 роки тому

    Is lower bound ie omega of n factorial, n?

  • @jamespogg
    @jamespogg 5 років тому +1

    Just because from your note k^k < (k+1)^k you are able to just plug this in to the right side of your equation? Why?

    • @laykefindley6604
      @laykefindley6604 3 роки тому

      This is my question. Would like clarification.

    • @AZ-nu8bq
      @AZ-nu8bq 3 роки тому +1

      @@laykefindley6604 by transitivity of inequalities. (k+1)k^k strictly less than (k+1)(k+1)^k implies (k+1)! strictly less than (k+1)(k+1)^k, and strictly less than implies less than or equal to. Which is how we get to 7:00

    • @laykefindley6604
      @laykefindley6604 3 роки тому

      @@AZ-nu8bq don't you lose the = part? If (k+1)! could be equal to (k+1)(k)^k but it can't be equal to (k+1)(k+1)^k because it is stricly less than so you lose the

    • @AZ-nu8bq
      @AZ-nu8bq 3 роки тому +1

      @@laykefindley6604 a

    • @laykefindley6604
      @laykefindley6604 3 роки тому

      @@AZ-nu8bq no that's not correct. If you plot the inequalities x

  • @idon_tknow4423
    @idon_tknow4423 3 роки тому

    Derive the execution time complexity in terms of the Big-O notation of the execution time function, T(n)= 2^n +4 n^3 +5n . Show your work clearly and provide the values for c and f(n) ????

  • @tiktokcollecter3867
    @tiktokcollecter3867 2 роки тому

    nice one

  • @narendratraders6633
    @narendratraders6633 6 років тому +1

    sir can you solve ?
    prove that log(n)=O(n) please

  • @user-tu7qn6vx8n
    @user-tu7qn6vx8n 5 років тому +2

    Why (k+1)k! change to (k+1)! in 5:01

  • @channelbangmamat7119
    @channelbangmamat7119 6 років тому

    why does (k+1)(k+1)^k turn to (k+1)^(k+1)?

    • @randerson112358
      @randerson112358  6 років тому +1

      That is just algebra imagine (k+1) = a, so we get
      (k+1)(k+1)^k = (a)(a)^a-1 = a^(a-1+1) = a^a
      Now let's plug back in (k+1) for a to get the following:
      a^a = (k+1)^(k+1).

    • @channelbangmamat7119
      @channelbangmamat7119 6 років тому

      I'm sorry for asking again, but how does (a)(a)^a-1 transform to a^(a-1+1) then to a^a? Thanks

    • @gabrielanavar9146
      @gabrielanavar9146 6 років тому

      its an identity, when you have the same base and you are multiplying, in this case it is a, you can add up the exponents and keep the same base so for example 2^6 * 2^2 = 2^8

  • @fredrikullman9349
    @fredrikullman9349 5 років тому

    so .. can it be proven ?? asking for a friend

  • @Asmrnerd10
    @Asmrnerd10 4 роки тому +3

    Your videos are ok... Very little to no explanation tho.

    • @randerson112358
      @randerson112358  4 роки тому

      Hhmmm.... okay, thanks for the comment and watching all of my videos! Sorry you couldn't understand my explanations.
      Hopefully you will have better luck elsewhere !

    • @bern1223
      @bern1223 3 роки тому

      @@randerson112358 I think he was just trolling.

  • @manishkumar-sw5xp
    @manishkumar-sw5xp 5 років тому +3

    anyone from india