Proof that the Sequence {1/(n^2+4)} Converges using the Definition of a Limit

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  • Опубліковано 12 січ 2025

КОМЕНТАРІ • 26

  • @sieni221
    @sieni221 4 роки тому +16

    Thank you for this. As a freshman maths major my real analysis professor is extremely confusing. This video was much more clear even tho im not native English speaker.

    • @TheMathSorcerer
      @TheMathSorcerer  4 роки тому +1

      You're very welcome!

    • @Put_in_type
      @Put_in_type 3 роки тому

      Hnn.... So "Batchelor of Science in mathematics " is " maths major" there.... The syllabus is same too i guess btw That's what it's called here.

    • @ebhojayejuliet9728
      @ebhojayejuliet9728 Рік тому

      Fellow math major here with a hella confusing professor

  • @tecnologia8507
    @tecnologia8507 4 роки тому +5

    Hi there,
    at 2:14 why are you comparing 1/(n^2 + 4) with 1/(n^2) ?
    Thanks in advance.

    • @Podzhagitel
      @Podzhagitel 10 місяців тому

      it’s the same kind of function but bigger

  • @kartikeyrathi6304
    @kartikeyrathi6304 2 роки тому +4

    Umm I have a small doubt
    sm1 willing to clarify ?
    the doubt is that 1/n2+4

  • @SonMulti
    @SonMulti 4 роки тому +3

    Why did you replace n^2 + 4 with n^2???

  • @Kudravets-Diana
    @Kudravets-Diana 3 роки тому +1

    Can someone help me with that question:
    How to prove it by the defination of limit ?
    lim n->infinty 1/2^n =0 ?

  • @tshredfly3997
    @tshredfly3997 Рік тому

    I'm watching this video at the end of 2023, let's hope someone will respond, in the first step of the proof, you have chosen N > 1/sqrt(ε), meanwhile I noticed that our professor, usually says that we need to put a condition on n at the beginning and then after proving that limit by definition, he uses the A.P to get that condition and finishes the proof, I'm kinda confused, also if I were asked to determine a limit of a sequence and prove it, is it correct just to calculate it as we used to do in high school for example lim 1/x = 0 and then prove it?

  • @sblue2614
    @sblue2614 5 років тому +2

    What happens when the denominator isnt always positive? For example in this 3n-1/4n^2-2n-6??

    • @TheMathSorcerer
      @TheMathSorcerer  5 років тому +2

      yeah you would have to break it up and rewrite it maybe, i'd have to write it all down but you would have, assuming I factored correctly here, |(3n -1)/((2)(n + 1)(2n - 3))| = 3, tricky I know, then from there you have
      |3n - 1|/(2n(n + 1)) and then break it up using the triangle inequality
      the idea is if you have like , 1/(2n - 3) you can do,
      1/(2n - 3) = 3, so that's 1/(2n - 3) = 3
      super clever/super useful technique, hope this helps:)

    • @kenbob1071
      @kenbob1071 5 років тому

      @@TheMathSorcerer That's a really cool trick to create a valid inequality with a single "n" term.

  • @Charjallz
    @Charjallz 5 років тому +3

    What if you had something like "n+1" in the numerator? You would then want to make the numerator bigger, right? And how?
    I have the problem 2n + 1 / 3n^2 + 2
    I can make the denominator smaller by making it 3n^2, but I don't know what to do after that.

    • @TheMathSorcerer
      @TheMathSorcerer  5 років тому +6

      write it as 2n/(3n^2 + 2) + 1/(3n^2 + 2)

    • @Charjallz
      @Charjallz 5 років тому +1

      @@TheMathSorcerer Thanks for the quick reply! That does help!

    • @TheMathSorcerer
      @TheMathSorcerer  5 років тому +1

      awesome!

    • @sportmaster2586
      @sportmaster2586 2 роки тому

      @@TheMathSorcerer Could you do instead 2n + 1 / 3n^2 + 2 < 2n + 1 / 3n^2 < 2n + n / 3n^2 < 1/n, then choose n to be any natural number greater than 1 / epsilon ?

  • @Gratitudeprayer
    @Gratitudeprayer 2 роки тому +1

    Thanks a lot !

    • @TheMathSorcerer
      @TheMathSorcerer  2 роки тому +1

      You are very welcome! I am so glad this helped someone:)

  • @ianroydayanan1102
    @ianroydayanan1102 3 роки тому

    What about finding the N in epsilon
    n / n^2 + 1

  • @yBazo82
    @yBazo82 4 роки тому +1

    High quality video

  • @oliverhoughton4598
    @oliverhoughton4598 3 роки тому

    thank youiu