Fun proofs

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  • เผยแพร่เมื่อ 18 พ.ย. 2024

ความคิดเห็น • 78

  • @AzharLatif-d4z
    @AzharLatif-d4z 11 หลายเดือนก่อน +52

    This guy must be an ethical man, a man of pure vision in the societal, and personal spheres of his life .His love for all learners gleams in his style of teaching Mathematics, reaching the edges of chosen topics in real time. Stay Blessed.

    • @PrimeNewtons
      @PrimeNewtons  11 หลายเดือนก่อน +6

      Thank you. You sound very wise.

    • @gkotsetube
      @gkotsetube หลายเดือนก่อน

      You should also hear him sing with the Bob Marley tribute band, the Junior Whalers.

  • @georgesbv1
    @georgesbv1 11 หลายเดือนก่อน +42

    (2k+1)^2 -1 = 2k * 2(k+1) = 4k*(k+1)
    It doesn't matter if k is even or odd, one of k or k+1 is divisible by 2 (and so is their product)

    • @PrimeNewtons
      @PrimeNewtons  11 หลายเดือนก่อน +2

      I knew I should that but somehow, I went the way of the wasteful 😂

    • @wafflaaar1067
      @wafflaaar1067 11 หลายเดือนก่อน

      I arrived at that logic too.

    • @Grecks75
      @Grecks75 3 หลายเดือนก่อน

      That's what I came up with in less than a minute.

    • @davidbrisbane7206
      @davidbrisbane7206 หลายเดือนก่อน +1

      ​@@PrimeNewtons
      It's never a waste of effort to solve a problem a different way.

  • @crsmtl76
    @crsmtl76 หลายเดือนก่อน +1

    Using mathematics to light up smiles is a such a blessing. Thank you Coach! 🙏

  • @JustJulezJulezing
    @JustJulezJulezing 11 หลายเดือนก่อน +7

    I don’t know how to describe it but most teachers I had taught math in a very cold and sterile way. You explain things in such a warm compassionate manner. Even if I don’t grasp the concept right away, I don’t feel like an imbecile after watching. Really glad I found your channel.

  • @CasiMediocre
    @CasiMediocre 2 หลายเดือนก่อน +1

    I found it funny that he said "let's get into the video ☺️" almost halfway through the video

  • @AbouTaim-Lille
    @AbouTaim-Lille 11 หลายเดือนก่อน +17

    The proof is easy without induction.if a is odd then a-1, and a+1 are even numbers and since they are consecutive even numbers then one of them is divisible by 4. So that their multiplication is divosible by 8. And their multiplication is (a-1)(a+1) =a²-1

    • @PrimeNewtons
      @PrimeNewtons  11 หลายเดือนก่อน +4

      Smart!

    • @robertlunderwood
      @robertlunderwood 11 หลายเดือนก่อน

      That was my proof.

    • @darcash1738
      @darcash1738 11 หลายเดือนก่อน

      That's an awesome way of doing it!

  • @jensberling2341
    @jensberling2341 11 หลายเดือนก่อน +1

    Loveable and lovely. Enjoyable every second of the presentation

  • @WahranRai
    @WahranRai 11 หลายเดือนก่อน +2

    10:33 remark that 4(k^2 + k) = 4*k(k+1) ---> k and k+1 are 2 consecutive number ----> one of them is even --->
    a^2 - 1 is divisible by 8.
    My demo is :
    Let a = 2k+ 1 an odd number ---> a^2-1 = (a+1)(a-1) = (2k+1 +1)(2k+1 -1) = (2k+2)(2k) = 4*(k+1)*k --->divisible by 8

  • @bobbobby7654
    @bobbobby7654 11 หลายเดือนก่อน +1

    Oh, fascinating dive into the intricacies of odd numbers and their mystical relationship with the number 8! Reminds me of the profound lyrics from "We Need Cash" - "I bought an electric guitar, I rented a shiny car." Just like odd numbers, life's equations seem to dance in mysterious patterns. By the way, did anyone notice that elusive secret cat in the background? A subtle nod to the feline chorus singing "nya ;3" in the song. Life's oddities and hidden references, what a peculiar symphony! Keep on calculating the enigma of existence!

    • @themathhatter5290
      @themathhatter5290 11 หลายเดือนก่อน

      I never expected a Tally Hall reference in a math teacher's comments.

  • @vaibhavsrivastva1253
    @vaibhavsrivastva1253 11 หลายเดือนก่อน

    A quick way to prove that a^2 - 1 is divisible by 8, for every odd number a, is :-
    Let a = 2k + 1, where k is an integer.
    Let x = a^2 - 1
    => x = (a+1)(a-1) = (2k + 1 + 1)(2k + 1 - 1) = 2(k+1) * 2k = 4 * k(k+1)
    => x = 8 * k(k+1)/2
    Now, we know that n(n+1)/2 is just the sum of all natural numbers from 1 to n (the sum being another natural number), and since all natural numbers are also integers, we can say that the sum is also an integer (note : it is of no importance whether this integer is positive, negative, or even zero).
    So, x = 8 * [integer]
    => x / 8 = [integer] => (a^2 - 1)/8 = [integer]
    => (a^2 - 1) mod 8 = 0
    Hence, a^2 - 1 is divisible by 8, for any and all odd numbers (here, 'a').
    P.S. :-
    Food for thought : How would we prove that n(n+1)/2 is necessarily an integer for an integral n, given that n(n+1)/2 is a natural number for a natural n? Or, is this assumption wrong in itself?

  • @debjanimukherjee502
    @debjanimukherjee502 11 หลายเดือนก่อน +2

    Presentation is awesome

  • @carltompkins3282
    @carltompkins3282 11 หลายเดือนก่อน +1

    That was a fun problem thanks mate 😊 I like these simpler ones I can understand and can get engaged in. ✅

  • @idkman640
    @idkman640 11 หลายเดือนก่อน

    If a²-1 is divisible by 8,
    Then,
    (a²-1)/8=n
    =>a²-1=8n -(i)
    (n belongs to set of integers)
    {(a+2)²-1}/8=k
    =>(a+2)²-1=8k -(ii)
    (k belongs to set of integers)
    From (i) & (ii),
    It is clear that (a²-1) and {(a+2)²-1} are even numbers as they both equate to a certain integer being multiplied by 8.
    So,
    =>(a+2)²-1-(a²-1)=2x
    =>a²+4a+4-1-a²+1=2x
    =>4a+4=2x
    =>a=(x/2)+1
    Here,For every value of x for which a is an integer is where a is odd.
    As,a is odd when a²-1 is divisible by 8 then conversely a²-1 is divisible by 8 when a is odd.

  • @JMcMillen
    @JMcMillen 2 หลายเดือนก่อน

    I noticed a sequence I'm familiar within this proof. If A=2K+1 then (A^2-1)/8 = K*(K+1)/2
    It's the triangle numbers. It even holds up if K is a negative number.

  • @SpennyBoi
    @SpennyBoi 11 หลายเดือนก่อน

    Start off with an integer a
    Double it
    Add one (this is k)
    Square it
    Minus 1
    And divide it by 8
    Following this you get
    a
    2a
    2a + 1
    4a^2 + 4a + 1
    4a(a + 1) and now it should be clear that when we divide it by 8 to get a(a + 1)/2 either a or a + 1 is even because a is an integer showing that we can divide one of those by 2 and multiply the remaining numbers to form a new integer.

  • @gamesofsteffen9159
    @gamesofsteffen9159 11 หลายเดือนก่อน

    You can do the second proof with induction, which seems useful in the context of the first proof, showing how it is done properly.

  • @alposmanagaoglu7352
    @alposmanagaoglu7352 11 หลายเดือนก่อน +4

    …we conclude that life is non-linear 😊

  • @rcnayak_58
    @rcnayak_58 11 หลายเดือนก่อน

    Once we have noted that a² - 1 = 4k² + 4 k, we can, taking 4k as common, write a² - 1 = 4k (k+1) = 4 . k(k+1). Notice that k(k+1) is the product of two consecutive numbers, the product of which is always an even number, say 2t , where t is any even or odd number. Then our a² - 1 becomes 8t, that is divisible by 8.

  • @chaosredefined3834
    @chaosredefined3834 7 หลายเดือนก่อน

    If a = 1, then a^2 - 1 = 0, which is divisible by 8.
    Assume that k is an odd number such that, if a = k, then a^2 - 1 is divisible by 8. Consider a = k+2. So, a^2 - 1 = (k + 2)^2 - 1 = k^2 + 4k + 4 - 1 = k^2 - 1 + 4(k+1). Since k^2 - 1 is divisible by 8, we only need to show that 4(k+1) is divisible by 8. Note that k is odd, so k+1 is even. 4 times an even number is a multiple of 8, so 4(k+1) is a multiple of 8.
    Since it's true for a = 1, then by what we just argued, it's true for a = 3. Therefore, it's true for a = 5. etc...

  • @diogochadudmilagres4533
    @diogochadudmilagres4533 2 หลายเดือนก่อน

    Newton, I choose a² -1 = (a + 1)(a - 1). So, a + 1 = 2k + 2, a - 1 = 2k, and a² -1 = (a + 1)(a - 1) = (2k + 2)*2k = 4k² + 4k. After, putting 4k in evidence, we have 4k(k + 1). So, if k is odd, k + 1 is even, and if k is even, k + 1 is odd. Any "Even times Odd" resullts in a Even. Hence, we have 4k(k + 1) = 4.Even = 4.2t = 8t, divisible by 8

  • @chrisrybak4961
    @chrisrybak4961 11 หลายเดือนก่อน

    Or just note that (a^2-1) = (a-1)(a+1), so if a=2n+1 (ie an odd number), then (a^2-1)=2n.2.(n+1) which always contains 2x2x2 whether n is odd or even => divisible by 8

  • @ChimezieFredAnaekwe
    @ChimezieFredAnaekwe 11 หลายเดือนก่อน +1

    With mathematical induction I might have the chance to live forever.

  • @flight7218
    @flight7218 11 หลายเดือนก่อน +1

    It is sufficient to study the remainders of a modulo 8 which are 0,1,2,3,4,5,6,7

    • @Curufin1984
      @Curufin1984 11 หลายเดือนก่อน

      Yes, that was also my own though. And you even only have to check 1,3,5,7 which I would call trivial.
      The "problem" is you have to give an argument that modulo arithmetic works (i.e. a*b (mod n) = a (mod n) * b(mod n) and a+b (mod n) = a (mod n) + b (mod n)). Not hard, but not self-evident.

  • @dububo
    @dububo 11 หลายเดือนก่อน +1

    a = 2k + 1.
    a² - 1 = (a + 1)(a - 1) = (2k + 1 + 1)(2k + 1 - 1) = (2k + 2)(2k) = 4k(k + 1).
    If k is even, then 4k(k + 1) = 4(2q)(k + 1) = 8q(k + 1), which is divisible by 8.
    If k is odd, then k + 1 is even, so 4k(k + 1) = 4k(2q) = 8kq, which is divisible by 8.

  • @CroneoRegion
    @CroneoRegion 11 หลายเดือนก่อน +3

    The second proof you did in the video is similar to a proof I did in a university project. I was deriving the formula for something in Knot Theory. Essentially, the formula needed to output an integer, and I actually had two parts of it. One of the parts hypothetically produced double of what I was needing (so I multiplied that by 1/2) but I didn't have a guarantee that it was even. The only guarantee I found was if I could show (x^2 - x) was always even, so I did something similar to what you did. I later realised that you could factor (x^2 - x) into x(x-1). If the input to that function is an integer, then x(x-1), or in your case x(x+1) is the product of two consecutive integers. This would prove its even, as I think there's a theorem out there where for any n consecutive integers, you are guaranteed that one of them will be divisible by n. When n = 2, one of the 2 consecutive integers is divisible by 2, meaning whatever product of the consecutive integers would have 2 as a factor, making it even. The way we both did it is fine, but that was another way it could be proven.

    • @Blade.5786
      @Blade.5786 11 หลายเดือนก่อน +1

      My solution was simply:
      a² - 1 = (a + 1)(a - 1)
      Since a is odd, (a + 1) and (a - 1) are even.
      In any two consecutive even numbers, one of them will be a multiple of 4.
      Therefore, their product is divisible by 2 x 4 = 8.

  • @darcash1738
    @darcash1738 11 หลายเดือนก่อน

    and it seems like if you were to do it by induction would it be (2(k+1)+1)^2 - 1 that you need to check.
    so, (2k+3)^2 - 1.
    It's pretty nice since it follows basically the same process in factoring out an 8 as this one.
    (2k+3)^2 - 1 = 4k^2+12k+8
    = 4(k^2+3k+2)
    if k is even, m is some other interger:
    = 4(even + even + 2); (even numbers squared are even; 2k1(2k2+1) = 4k1k2+2k1 = 2(2k1k2+k1), so even times odd is even)
    = 4(2m1+2m2+2)
    = 8(m1+m2+1)
    if odd, q for some other interger:
    = 4(odd+odd+2); (odd nums squared are odd, odd*odd = odd)
    = 4(2q1+1+2q2+1+2)
    = 8(q1+q2+2)

  • @nasrullahhusnan2289
    @nasrullahhusnan2289 หลายเดือนก่อน

    a is odd --> a=2k±1
    a²-1=(2k±1)²-1
    =4k²±4k
    =4k(k±1)
    Note that 2 | (k±1)
    Hence 8 | a²-1

  • @darkkupo5162
    @darkkupo5162 11 หลายเดือนก่อน

    clarification, the error lies in the assumption that P(K+1) = P(K) + P(1). You can assume that you survive day K and if you can show you survive day K+1 then it would have to be the case that you can live forever. The reason your joke proof doesn't work is because the function cannot be broken the way you claim, not because you can't assume K.

  • @xyz9250
    @xyz9250 7 หลายเดือนก่อน

    You could also just factor k^2+k into k(k+1) one of them will be even number.

  • @Alessandro-1977
    @Alessandro-1977 11 หลายเดือนก่อน +1

    Grouping 4k(k+1) in 4(k^2+k), it easily turns out that k(k+1) is always even, either k is odd or even (if k is even, k+1 is odd and vice versa, thus k*(k+1) is always even)

  • @Uriboica
    @Uriboica 11 หลายเดือนก่อน

    U got me addicted to maths

  • @Arkapravo
    @Arkapravo 7 หลายเดือนก่อน

    Can you consider doing some basic Topology - I never grasped that subject!

    • @PrimeNewtons
      @PrimeNewtons  7 หลายเดือนก่อน +1

      Ha, that's a big ask. I'll see if I can get some friends to fill in for me

  • @sirak_s_nt
    @sirak_s_nt 11 หลายเดือนก่อน

    It obvious that for any number n, n²= 1,4,0 mod 8, 1 if n is odd and 4,0 when n is evenm
    Since a is odd a²= 1 mod 8
    Thus a²-1 is divisible by 8.

  • @davidbrisbane7206
    @davidbrisbane7206 11 หลายเดือนก่อน +2

    Let a = 8k + r, where k and r are integers and
    0 ≤ r ≤ 7.
    But since a is odd, then r = 1, 3, 5, or 7.
    So, a² = (8k + r)² = 8(8k² + 2kr) + r²
    So a² - 1 is divisible by 8 if r² - 1 is divisble by 8.
    We note that the only possible values of
    r² - 1 are 0, 8, 24, 48 which are all divisible by 8.
    So a² - 1 is divisible by 8 if a is odd.

  • @goldeneagleyt8652
    @goldeneagleyt8652 11 หลายเดือนก่อน +2

    Beautiful

  • @klementhajrullaj1222
    @klementhajrullaj1222 11 หลายเดือนก่อน

    Can you prove that: n^3 - n is divisible by 6, where n is a natural number?

  • @mosespeters5546
    @mosespeters5546 11 หลายเดือนก่อน

    Hi good day Prime Newtons. I love your videos and i have a question. How does this proof implies that a^2-1 is divisible by 8, for values of a which are odd only? Is it that an odd number squared is always odd?

    • @nanamacapagal8342
      @nanamacapagal8342 11 หลายเดือนก่อน

      if a is odd, then a^2 is odd. but the -1 makes it even.
      the proof in the video is to write a = 2k + 1 where k is an integer.
      a = 7 can be written as 2*3+1.
      a = 13 can be written as 2*6+1.
      a = -5 can be written as 2*(-3)+1.
      hope that helps clarify a few things

    • @mosespeters5546
      @mosespeters5546 11 หลายเดือนก่อน

      @@nanamacapagal8342 Hey there , thank you

  • @WhiteGandalfs
    @WhiteGandalfs 7 หลายเดือนก่อน

    Well: (5:20) Just by adjusting from an undisputed "survive every day" to a probability of surviving a day (maybe even in dependence from age and other factors), we make a valid scientific base for survivability analysis. Nonetheless, IF you INDEED survive every daily unit, you INDEED live forever. That is absolutely true - even if that "if" is not at all undisputed in real life. But IF it would hold, the "life forever" holds as well.
    You are allowed to make assumptions in your models. You just have to track what you do for what purpose. I don't count that as an "illogical" construct. It just is an example for the responsibility of a scientist for judgement of his data source and the judgement of the conclusions he draws from his data. You just showed in your model that infinite life is possible by infinitely surviving every day - completely analogue to counting to infinity or to dividing into infinitely small differentials - which you may instantiate as a model for certain examinations, DESPITE never being able to factually do so in real life.

  • @Jianlong-xp5li
    @Jianlong-xp5li 11 หลายเดือนก่อน +2

    Can you please make a video about log and natural log

    • @PrimeNewtons
      @PrimeNewtons  11 หลายเดือนก่อน +2

      That's a wide topic. Is this algebra or calculus?

    • @Jianlong-xp5li
      @Jianlong-xp5li 11 หลายเดือนก่อน

      Both

    • @Jianlong-xp5li
      @Jianlong-xp5li 11 หลายเดือนก่อน

      Maybe calculus

  • @rob876
    @rob876 11 หลายเดือนก่อน +1

    since a is odd,
    a = 2n + 1 where n is an integer
    so a^2 - 1 = (a - 1)(a + 1) = 2n(2n + 2)
    = 4n(n + 1)
    but n(n + 1) is divisible by 2 because either n or n + 1 is even.
    therefore 4n(n + 1) is divisible by 8

  • @ALIEAKAMARA-gy2vo
    @ALIEAKAMARA-gy2vo 11 หลายเดือนก่อน

    Sir I need your help please

  • @adamhanna9940
    @adamhanna9940 11 หลายเดือนก่อน

    2k+1 , k>1. As the first + odd is 3

  • @xenumi
    @xenumi 5 หลายเดือนก่อน

    I think I found a counter-example

  • @novasleepy
    @novasleepy 11 หลายเดือนก่อน

    Can you do the Cbrt of i

    • @nanamacapagal8342
      @nanamacapagal8342 11 หลายเดือนก่อน

      we're gonna need some euler's formula e^(iT) = cos(T) + isin(T)
      get ready

  • @embracinglogic1744
    @embracinglogic1744 11 หลายเดือนก่อน +1

    Assume my head is frozen on day k.

  • @dankaxon4230
    @dankaxon4230 11 หลายเดือนก่อน +1

    what if you were a stillborn

    • @AzharLatif-d4z
      @AzharLatif-d4z 11 หลายเดือนก่อน

      But Souls are eternal as fire-fly.

    • @Luke_the_Duke-id4uo
      @Luke_the_Duke-id4uo 8 หลายเดือนก่อน

      Simply, P(1) would not be true.

    • @bart2019
      @bart2019 8 หลายเดือนก่อน

      Then you wouldn't have been watching this video.

  • @vemarj2802
    @vemarj2802 11 หลายเดือนก่อน

    Also kinda cool, btw:
    for all n >= 0:
    2^(2(2n+1)) + 1 = 0 mod 5
    Easy proof by induction too.
    In binary, they are these numbers:
    101,
    1000001,
    10000000001,
    100000000000001, etc.

  • @reamartin6458
    @reamartin6458 11 หลายเดือนก่อน +1

    The answer is: [Life = Yeshua]

  • @adamhanna9940
    @adamhanna9940 11 หลายเดือนก่อน

    I meant k> 0

  • @ivanhuertas5307
    @ivanhuertas5307 6 หลายเดือนก่อน

    it is guaranteed of course it is that you can live forever John 11:25 Jesus said unto her, I AM the resurrection and the life; he that believes in me, though he is dead, yet shall he live;
    John 11:26 and whosoever lives and believes in me shall never die. Believest thou this?

  • @Jianlong-xp5li
    @Jianlong-xp5li 11 หลายเดือนก่อน

    Hello

  • @glorrin
    @glorrin 11 หลายเดือนก่อน

    I have a better way to (maybe not) live forever.
    I. You have the ability to live for 1 day.
    II. Let's assume you have the ability to live for k days.
    What about k + 1 days ?
    well + is commutative, so k+1 = 1 +k
    We know you have the ability to live for 1 day because of I.
    it remains k days,
    and thanks to II. we knoe youhave the ability to live for k days.
    therefor you can live for 1+k days
    Conclusion you will live forever.