Prove that n^3 + 2n is divisible by 3 using Mathematical Induction

แชร์
ฝัง
  • เผยแพร่เมื่อ 26 เม.ย. 2022
  • Prove that n^3 + 2n is divisible by 3 using Mathematical Induction
    If you enjoyed this video please consider liking, sharing, and subscribing.
    Udemy Courses Via My Website: mathsorcerer.com
    My FaceBook Page: / themathsorcerer
    There are several ways that you can help support my channel:)
    Consider becoming a member of the channel: / @themathsorcerer
    My GoFundMe Page: www.gofundme.com/f/support-ma...
    My Patreon Page: / themathsorcerer
    Donate via PayPal: paypal.com/donate/?cmd=_s-xcl...
    ***********Udemy Courses(Please Use These Links If You Sign Up!)************
    Abstract Algebra Course
    www.udemy.com/course/abstract...
    Advanced Calculus Course
    www.udemy.com/course/advanced...
    Calculus 1 Course
    www.udemy.com/course/calculus...
    Calculus 2 Course
    www.udemy.com/course/calculus...
    Calculus 3 Course
    www.udemy.com/course/calculus...
    Calculus Integration Insanity
    www.udemy.com/course/calculus...
    Differential Equations Course
    www.udemy.com/course/differen...
    College Algebra Course
    www.udemy.com/course/college-...
    How to Write Proofs with Sets Course
    www.udemy.com/course/how-to-w...
    How to Write Proofs with Functions Course
    www.udemy.com/course/how-to-w...
    Statistics with StatCrunch Course
    www.udemy.com/course/statisti...
    Math Graduate Programs, Applying, Advice, Motivation
    www.udemy.com/course/math-gra...
    Daily Devotionals for Motivation with The Math Sorcerer
    www.udemy.com/course/daily-ma...
    Thank you:)

ความคิดเห็น • 22

  • @johngreen3543
    @johngreen3543 2 ปีที่แล้ว +5

    I love induction proofs, both the weak and strong forms. So, do some more of these The Z is Zahlen in German. The early mathematicians who developed set theory (like Cantor) used this letter. N for natural numbers,R for real numbers, Q for the rationals. Your proof was exceptionally well done. Two thumbs up

  • @DavesMathVideos
    @DavesMathVideos 2 ปีที่แล้ว +3

    Recently did a similar proof over on my channel, except I used something similar to the pigeonhole principle. It's the "Indonesian Olympiad" question in my play list. Since we want that n^3 + 2n ≡ 0 (mod 3) and we can factor n^3 + 2n = n(n^2 + 2), we can consider the following. If n ≡ 0 (mod 3), then obviously the product is divisible by 3. If n ≡ 1 (mod 3), then (n^2 + 2) = 9k^2 + 6k + 3, which is clearly divisible by 3. Last if n ≡ 2 (mod 3), then we can write (n^2 + 2) as (9k^2 - 6k + 3) which again, is divisible by 3.

  • @JoelRosenfeld
    @JoelRosenfeld 2 ปีที่แล้ว +2

    This seems really involved for what it is. It’s a nice introduction to induction, but really modular arithmetic makes this ludicrously short with three cases to check.

  • @user-if1gj2wh5c
    @user-if1gj2wh5c 2 ปีที่แล้ว +4

    Doing induction in school right now, had this exact problem and didn't know how to do it and you upload this lol

  • @stevenzimmerman3945
    @stevenzimmerman3945 2 ปีที่แล้ว +2

    I would love to see a video that misuses mathematical induction. For example, proving that all horses are the same color.

  • @CarolynFahm
    @CarolynFahm 2 ปีที่แล้ว +2

    Fascinating! Keeping all the steps allows us to follow along with this beautiful mathematical proof.

  • @tjalferes
    @tjalferes 2 ปีที่แล้ว

    Thanks

  • @antonim8359
    @antonim8359 ปีที่แล้ว

    Wow, that's a great video! Really, I think thanks to that I fully grasped the concept of mathematical induction proof :))

  • @stevenzimmerman3945
    @stevenzimmerman3945 2 ปีที่แล้ว +2

    Great Induction Proof! I like how you handled both the inductive hypothesis and the inductive step. Using the inductive hypothesis is often difficult for students learning induction for the first time.
    By the way, The Principal of Mathematical Induction is a school administrator. I think you meant the theorem, Principle of Mathematical Induction.

  • @peterkistler3537
    @peterkistler3537 2 ปีที่แล้ว +2

    I solved it the same way on my own! Have you ever demonstrated any strong induction problems? I don't think I ever understood that process quite right.

    • @TheMathSorcerer
      @TheMathSorcerer  2 ปีที่แล้ว +2

      I should make some videos on that!

  • @irvngjuarez
    @irvngjuarez ปีที่แล้ว

    Beautiful

  • @acdude5266
    @acdude5266 2 ปีที่แล้ว +3

    What is the background tool you are using?

    • @TheMathSorcerer
      @TheMathSorcerer  2 ปีที่แล้ว

      it's an older program called smoothdraw

    • @acdude5266
      @acdude5266 2 ปีที่แล้ว

      @@TheMathSorcerer Thank you!Nice proof!

  • @dolevmazker736
    @dolevmazker736 2 ปีที่แล้ว +1

    top notch video brother

  • @capitanp.findus6576
    @capitanp.findus6576 2 ปีที่แล้ว

    I don't understand if ,by your proof, this propriety is valid for n ∈ N, or also for n ∈ Z. That's because, from what is my grasp on induction, if u want to prove it also for negative numbers u should show that if the propriety is valid for n, then is valid for n-1. Am i wrong?

    • @JoelRosenfeld
      @JoelRosenfeld 2 ปีที่แล้ว

      Since n^3 + 2n is an odd function, replacing n with -n, you get -(n^3+2n), and since n^3+2n is divisible by 3 so is its negative