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Number Theory | Inverses modulo n

We give a characterization of numbers which are invertible modulo n.

Пікірлер: 37

  • @thinguyen8865
    @thinguyen88654 жыл бұрын

    Thanks you teacher Penn for dedicating time and energy to create awesome math videos that helps simplify math like this. It helps students around the world who struggle with math a lot.

  • @azharlatif6228
    @azharlatif62283 жыл бұрын

    Michael Penn is Super human embodying as Mathematician, Mountaineer, Diver and what not. Saw his Q n A footage to know him. Stay Blessed Michael !!!

  • @gorgzilla1712
    @gorgzilla17123 жыл бұрын

    Thank you so much for being so clear and concise in all these videos; really helps a lot! Subscribed.

  • @georgesadler7830
    @georgesadler78302 жыл бұрын

    Professor Penn, thank you for fantastic analysis on Inverses modulo n. These are classic topics in Number Theory.

  • @azizketata3241
    @azizketata32412 жыл бұрын

    the tyoe of teacher who will fuckk you up if you're not attentive . Keep lifting man.

  • @zianwang2897
    @zianwang28974 жыл бұрын

    Great work! Keep it up.

  • @ramakrishnasen4386
    @ramakrishnasen43863 жыл бұрын

    Try taking off your earphones and watching this video! The magic is, you'll still understand what he wants to explain!!

  • @ryanl3184

    @ryanl3184

    3 жыл бұрын

    Yeah... Speakers are just bigger versions of earphones.

  • @Nothingtonnobodson

    @Nothingtonnobodson

    3 жыл бұрын

    @@ryanl3184 lol

  • @PunmasterSTP
    @PunmasterSTP3 жыл бұрын

    I know that you just discussed inverses, but I have to say that this video was singular. Thanks again for making all of these!

  • @kakalibiswas1312
    @kakalibiswas13123 жыл бұрын

    Thanks sir for giving free knowledge of number theory

  • @MyOneFiftiethOfADollar
    @MyOneFiftiethOfADollar2 жыл бұрын

    Noticed for arbitrary modulus n that (n-1)(n-1)==(-1)(-1)=1 (mod n) Put another way, n-1 is it’s own inverse (mod n). Also consistent with n and n-1 being relatively prime. Special case of this is what you showed (8)(8)==1 (mod 9)

  • @Walczyk
    @Walczyk3 жыл бұрын

    michael penn is doing the world a great service, really for anyone interested in pure math

  • @she_wizzdom4410
    @she_wizzdom44103 жыл бұрын

    Finally understood it ! Thanks

  • @tiandao1chouqin
    @tiandao1chouqin4 жыл бұрын

    Nice work. At 7:32, about the reverse direction proof, you said you proved it in the channel before, could you provide the link? Thanks!

  • @hypnovia
    @hypnovia8 ай бұрын

    If you can have the inverse of a number mod n… what’s stopping there from being an inverse of a MATRIX mod n? What if det(M) mod n is equal to 0, or not relatively prime to n?

  • @sedasavas7017
    @sedasavas7017 Жыл бұрын

    Thank you Mr. Penn 🙏🙏🙏

  • @Tytyshippy
    @Tytyshippy10 ай бұрын

    GOOD.

  • @Ensivion
    @Ensivion4 жыл бұрын

    so for only prime n, do each of the non-zero minimal residues have an actual 'modulo inverse', and n-1 always is its own inverse, I have a feeling this is very important when studying primes.

  • @TJStellmach

    @TJStellmach

    3 жыл бұрын

    Yes, in fact this criterion means that any ring of integers modulo a prime number is also a field, and therefore a host of theorems which hold in fields are available.

  • @ren5124
    @ren5124 Жыл бұрын

    How do we prove that these inverse pairs are unique?

  • @2on1masti9
    @2on1masti94 жыл бұрын

    Thank you sir

  • @williamjones3731
    @williamjones37314 жыл бұрын

    Great videos

  • @MichaelPennMath

    @MichaelPennMath

    4 жыл бұрын

    Thanks!

  • @chrisjuravich3398
    @chrisjuravich339810 ай бұрын

    So influenced am I by these videos that I find myself saying “good“ after each time I make a true statement of fact.

  • @GauravKumar-bk7hh
    @GauravKumar-bk7hh4 жыл бұрын

    mast

  • @kArnAgePT
    @kArnAgePT4 жыл бұрын

    good

  • @ToanPham-wr7xe
    @ToanPham-wr7xe6 ай бұрын

    😮

  • @kobethebeefinmathworld953
    @kobethebeefinmathworld9533 жыл бұрын

    I'll say it's more like a ring theory problem

  • @abdelrhmanahmed1378

    @abdelrhmanahmed1378

    3 жыл бұрын

    because its a ring theory problem !:)

  • @mohammedsamir5142
    @mohammedsamir5142 Жыл бұрын

    6:32 Could anyone explain this step for me?!

  • @mysto5107

    @mysto5107

    Жыл бұрын

    it's a theorem that any linear combination of 2 numbers a and b, has to be a multiple of the gcd. since the only divisor of 1 is 1, then the gcd has to be 1.

  • @sgssergio
    @sgssergio4 жыл бұрын

    Hi teacher, in 1:56 you write 2^-1 = 5 mod 9 , 5^-1 cong 2 mod 9. In the first why do you use equal sumbol and not congruence symbol instead?

  • @dominickmancine6033

    @dominickmancine6033

    3 жыл бұрын

    It's just a "typo". The multiplicative inverse of any number that's congruent to 2 (mod 9) is any number that's congruent to 5 (mod 9). But to avoid using all of those words people usually just say the inverse of 2 (mod 9) *is* 5. That implies equality, but congruence is really just a "loose" equality. I think whenever you say (mod n) you really should use the congruence symbol, but sometimes people forget. Also, in the comments on his videos people will use the = symbol because it's not obvious how to type the congruence symbol.

  • @jonatanorange6491
    @jonatanorange64913 жыл бұрын

    Great content, but Bruh, in the future recordings please stop missing steps and call them "tricks".

  • @mgd891
    @mgd891Ай бұрын

    hot