Mathematical Induction - Proving Divisibility by 4 (2 of 2: How to use the assumption)

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  • เผยแพร่เมื่อ 14 ต.ค. 2024
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ความคิดเห็น • 35

  • @Sir_Budginton
    @Sir_Budginton 6 ปีที่แล้ว +13

    Different method to how I learnt it, but still interesting to watch.

  • @jesuisravi
    @jesuisravi 3 ปีที่แล้ว +1

    E.W., you just keep getting better and better.

  • @bradleykukuk1921
    @bradleykukuk1921 5 ปีที่แล้ว +5

    Thank you for posting this... very helpful!

  • @MMarcuzzo
    @MMarcuzzo 6 ปีที่แล้ว +1

    I believe there's something wrong...
    You must prove that
    1. Induction basis (one k' which holds P(k')) (which is okay)
    then:
    2. If P(k) holds, then P(k+1) holds
    i.e:
    P(k) => P(k+1).
    So you shouldn't start your proof assuming P(k+1)...
    You have proven that P(k+1) => P(k), so...it doesn't seem correct to me.
    One way, being simplistic on notation here:
    5^k + 3 = 4P, P must be integer, our k must be non-negative integer (assumed true)(our P(k))
    so we must manipulate this initial expression so that P(k+1) holds:
    5^k+3 = 4P
    5^k = 4P - 3
    5^(k+1) = 20P - 15
    P is some integer, so: 5P is also some integer P
    5^(k+1) = 4P - 12 - 3
    5^(k+1) + 3 = 4(P-3)
    But P-3 is also some integer P
    5^(k+1) + 3 = 4P
    then, we got that: P(k) => P(k+1)

    • @RaffaHiTech
      @RaffaHiTech 6 ปีที่แล้ว

      He also showed that P(k)=>P(k+1) is true.

    • @hypercent
      @hypercent 6 ปีที่แล้ว

      @Mateus Marcuzzo:
      I disagree. It was shown that 5^(k+1)+3 is a multiple of 4 if 5^k+3 is as well. So P(k) => P(k+1) was indeed proven. You don't have to manipulate the assumption to get to your statement to prove. You just have to use it to show that the left-hand side of the statement to prove is indeed equal to the right-hand side.
      Also: In your proof you change the value of P multiple times. You should introduce a new variable instead, as was done in the video. For example, the statement "5P is some integer P" implies P=0, which is not what you mean.

    • @MMarcuzzo
      @MMarcuzzo 6 ปีที่แล้ว

      hypercent thanks for the answer. I've been thinking on this, and my conclusion is that I've learned something new today.
      About P: its okay, since I just want to represent that P is some integer. So some integer *4 is a multiple of 4. I could do P, P' and so on, as you suggest.

  • @tringuyen237
    @tringuyen237 2 ปีที่แล้ว

    thank you for the explanations my online class never provided!

  • @qinisekanicetyana8793
    @qinisekanicetyana8793 ปีที่แล้ว

    Wisely man❤✊

  • @williamduran9590
    @williamduran9590 6 ปีที่แล้ว +1

    Hi, May you do cardinality and infinite sets exercises??

  • @slyowusu99
    @slyowusu99 6 ปีที่แล้ว +1

    Brilliant and highly engaging. A natural. BTW. I do wish at the end of every maths lesson, everywhere, everyone stops, takes a breath and asks...and answers the question......how is this applicable in everyday activity. eg writing code for ......

    • @EpiCuber7
      @EpiCuber7 4 ปีที่แล้ว +2

      Well sometimes people do maths purely because it's interesting (pure mathematics), so it may not be the best idea to force students to only care about applications of math, when the math itself can be beautiful without necessarily having a purpose.

  • @malanhemal6574
    @malanhemal6574 3 ปีที่แล้ว +1

    I didn't quite understand 3:15, where you wrote 5*5^k +3 = 4*5^k + 5^k + 3 ?

    • @nathandam6415
      @nathandam6415 3 ปีที่แล้ว +5

      Multiplication is just simplified addition. 5*5^k is just 5^k+5^k+5^k+5^k+5^k, or 5 sets of 5^k. So using algebra you can change it to 4*5^k + 5^k.

    • @ScantaniouslyCombust
      @ScantaniouslyCombust 3 ปีที่แล้ว +1

      @@nathandam6415 thank god for you buddy! that cleared it up for me completely!

    • @malanhemal6574
      @malanhemal6574 3 ปีที่แล้ว +2

      @@nathandam6415 Thank you, for your time

  • @zasakai1000
    @zasakai1000 2 ปีที่แล้ว

    THANKYOU

  • @Fahodinho
    @Fahodinho 3 ปีที่แล้ว

    Cheers mate!

  • @unbound26z
    @unbound26z 6 ปีที่แล้ว +1

    thanks man already knew this but i really appreciate your channel

  • @rafaelbnn
    @rafaelbnn 6 ปีที่แล้ว

    I don't if it's correct but I learned that Z+ means all non-negative integers instead of positive integers. Can someone confirm it?

    • @icee562
      @icee562 4 ปีที่แล้ว +3

      that means the same thing

  • @maheemalhafiz5493
    @maheemalhafiz5493 ปีที่แล้ว

    Can someone tell me how is 5^k + P = Q?

  • @ANANDYADAVRAILWAY
    @ANANDYADAVRAILWAY 6 ปีที่แล้ว

    Thanks

  • @renkiemkhize2262
    @renkiemkhize2262 2 ปีที่แล้ว

    Why is it 4Q

  • @moherpimpson
    @moherpimpson 6 ปีที่แล้ว +2

    How old are the students learning this

  • @BaIIsDeep
    @BaIIsDeep 6 ปีที่แล้ว +2

    Can you please make vid about sin(x)÷x=1

    • @fres4xd3hhhf5
      @fres4xd3hhhf5 6 ปีที่แล้ว

      Joseph its a limit..

    • @BaIIsDeep
      @BaIIsDeep 6 ปีที่แล้ว

      I know it's the limit but I mean the prove of sin(x)÷x=1

    • @hazemsalem8495
      @hazemsalem8495 6 ปีที่แล้ว

      www.khanacademy.org/math/ap-calculus-ab/ab-derivative-rules/ab-derivtive-rules-opt-vids/v/sinx-over-x-as-x-approaches-0

    • @tamircohen1512
      @tamircohen1512 6 ปีที่แล้ว

      He has already made a video on it. It is split into 3 videos and it will all make sense by the third: th-cam.com/video/R1mEeQhgNuM/w-d-xo.html

  • @sunrain4820
    @sunrain4820 11 หลายเดือนก่อน

    Thank you🥰✌🏽🤓❤️‍🩹❤️‍🩹