Solving improper integrals without actually solving them! (part 1)

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  • Опубликовано: 18 ноя 2024

Комментарии • 62

  • @blackpenredpen
    @blackpenredpen  Месяц назад +8

    I used a double integral to solve a single improper integral
    ruclips.net/video/QDLDMDYxQ-0/видео.html

  • @bluu1939
    @bluu1939 Месяц назад +75

    Thank God, that Ramanujan spent at most 5 minutes on this problem so i dont have to spend 1 hour.

    • @bluu1939
      @bluu1939 Месяц назад +1

      Ramanujan's master theorem and/or Mellin

    • @xinpingdonohoe3978
      @xinpingdonohoe3978 Месяц назад

      @@bluu1939 when you look at his original proof of his master theorem, it actually makes intuitive sense. Still, I'd never have come up with it.

  • @iliqiliev
    @iliqiliev Месяц назад +9

    I didn't expect that I will encounter a calculus cliffhanger today

  • @xinpingdonohoe3978
    @xinpingdonohoe3978 Месяц назад +9

    Normally you'd be given the suggestion that a function must have an infinite limit of 0 for the infinite integral to have a chance to converge. cos(x²) and sin(x²) seem to shatter this.

    • @methatis3013
      @methatis3013 Месяц назад

      That's quite interesting because, for series, this does need to be true

  • @nmaedu.100
    @nmaedu.100 Месяц назад +3

    Great Work✅

  • @cdkw2
    @cdkw2 Месяц назад +1

    Lets go a series!

  • @benardolivier6624
    @benardolivier6624 5 дней назад

    The last curve is just the heartbeat of someone dying...

  • @damose267
    @damose267 Месяц назад +20

    great video, but why you still use Geogebra Classic 5 in 2024 lol

  • @orenfivel6247
    @orenfivel6247 Месяц назад +12

    We can assign I think we can assign a value for ∫cos(wt)dt and ∫sin(wt)dt by Laplace transform with s→0
    ∫cos(wt)dt⇒s/(s^2+w^2)→0
    ∫sin(wt)dt⇒w/(s^2+w^2)→1/w
    Ref dr peyam that released a video on Laplace transform exacly when you released that video

    • @cheeseparis1
      @cheeseparis1 Месяц назад

      I was about to write about Laplace transforms for the same reason. Videos released at the same time. This is a mathematical conspiration.

  • @williammartin4416
    @williammartin4416 Месяц назад

    Thanks!

  • @diogr22
    @diogr22 Месяц назад +2

    waiting on that next vid

  • @roboarjun
    @roboarjun Месяц назад +5

    did you just sponsor BMT (Berkeley Math Tournament)!?!!!

  • @AlokPatil-sz7er
    @AlokPatil-sz7er Месяц назад +1

    He is not pregnant but he never fails to deliver

  • @Calcprof
    @Calcprof Месяц назад +2

    Fresnel Integrals!

  • @artsmith1347
    @artsmith1347 Месяц назад

    And explanation of how the value for (3) is known would be interesting.

    • @Samir-zb3xk
      @Samir-zb3xk Месяц назад

      You can use Euler's formula to convert sin/cos into exponential functions and if you know the Gaussian integral the rest is straightforward

    • @emilianorosario5935
      @emilianorosario5935 Месяц назад

      create a function f(t) such that f(t) is the integral from zero to infinity of cos(tx^2) , then take the laplace transform of that function and you get an integral you can solve. math 505 made a video on it

  • @nizogos
    @nizogos Месяц назад

    I found the value of the integral of sin(1/x^2) to be sqrt(π/2)

  • @AndDiracisHisProphet
    @AndDiracisHisProphet Месяц назад +1

    the next video is about a combinatorics problem...

  • @Gemini_Huan
    @Gemini_Huan Месяц назад

    answer is sqrt(pi/2)

  • @rishii2296
    @rishii2296 Месяц назад +2

    *DAY 2* :
    One calc equation : What's the irl use of finding the volume when we rotate f(x) about a line using the Disc method, the Washer method etc, when we can simply.......
    Take the object and submerge it just below a given level of water of volume *v1 cubed units* and see the new reading of reaching the new greater value of *v2 cubed units* , and get the volume of the object as *v2-v1 cubed units* ??? [Done by Archimedes' Principle]

    • @unturnedd
      @unturnedd Месяц назад +1

      how will you know exactly how the volume changes depending on the radius?

    • @rishii2296
      @rishii2296 Месяц назад

      @@unturneddWith the help of a graduated beaker, which will contain readings like 100ml then 125ml and so on and also between the degrees.

    • @FunctionallyLiteratePerson
      @FunctionallyLiteratePerson Месяц назад

      1) not everything could be easily submerged (whether due to size or amount of water)
      2) not everything we want to get the volume of exists in real life. It's faster to compute then to go out of our way to make a real model of it
      3) you may want to only get the volume of a portion of it without cutting or otherwise modifying it, and it might not have uniform density

  • @rqlk
    @rqlk Месяц назад

    Unrelated to the video, but I’ve been trying to wrap my head around the function y = the xth root of x. How do I differentiate it, and how do I write it in terms of y. Also is it possible to anti-differentiate it. Mainly though I just want to figure out how to write that function in terms of y. I tried using inverse operations and got y^x = x. Then I took the log base y of both sides, but I came full circle and got x = log base y of x, which is no better than y^x = x. Furthermore I can find hardly any information about that specific function online.

    • @SparkDragon42
      @SparkDragon42 Месяц назад

      You should study it as y=e^(ln(x)/x), and to get an inverse function, you should look into the Lambert's W function defined as being the inverse function of x.e^x it might help (not sure but it's really good for this kind of problem where there's an x in the base and the exponent)

  • @jarikosonen4079
    @jarikosonen4079 Месяц назад +3

    If infinity is integer and multiple of any number including 2π, then what could it mean?
    But maybe not possible.

  • @draaagoo7799
    @draaagoo7799 Месяц назад +2

    i think i solved it , is it sqrt of (pi over 2)

    • @Samir-zb3xk
      @Samir-zb3xk Месяц назад +5

      Yes, I solved it by first doing t = 1/x, then differentiation under the integral (aka Feynman integration), with help from Euler's formula and the Gaussian integral

    • @draaagoo7799
      @draaagoo7799 Месяц назад

      @@Samir-zb3xk same but i used the fresnel integral insteqd of gausian

    • @Samir-zb3xk
      @Samir-zb3xk Месяц назад

      @@draaagoo7799 yea you can do the Fresnel integrals by making sin/cos into exponential functions through Euler's formula then Gaussian

    • @draaagoo7799
      @draaagoo7799 Месяц назад

      @@Samir-zb3xk But no i didnt do that , actually i did a U sub first U =1/x then i used feynman on the resulting integral . feynman gave us : F(a)=integral from 0 to infinity of sin(a* U^2)/U^2 wjen we derive we get a fresnel integral he soolved it in the video i used the result i integrated and i put a=1 ( hope you understood its hard to explain over a comment)

    • @Samir-zb3xk
      @Samir-zb3xk Месяц назад +1

      @@draaagoo7799 oh ok, yea thats pretty much the same thing I did. I just derived the result in the video using Euler's formula and the Gaussian integral

  • @VideoFusco
    @VideoFusco Месяц назад

    The integrals 1 and 2 do not diverge, they do not exist. In the same sense that the infinite sum of alternating addends 1 and -1 does not exist.

    • @SparkDragon42
      @SparkDragon42 Месяц назад

      That's what diverging means. To diverge is to not converge, and if it doesn't exist, then it doesn't converge, so it diverges.

    • @VideoFusco
      @VideoFusco Месяц назад

      @@SparkDragon42 no, "diverge" is not the same that "not converge", "diverge" means "go to infinity".

    • @SparkDragon42
      @SparkDragon42 Месяц назад

      @@VideoFusco let's agree to disagree as our definitions are obviously different

    • @nightytime
      @nightytime Месяц назад

      "divergence by oscillation"

    • @VideoFusco
      @VideoFusco Месяц назад

      @@SparkDragon42 definitions are not debatable or sensitive to personal tastes: the fundamental difference between an integral (or a series) that diverges (that is, that has an infinite result) and one that does not exist is that the first remains divergent even if you generalize the definition of integral (or series), while with generalizations the integrals (or series) that have no result can become convergent: if, for example, you take the sum of Cesaro or Holder, all the divergent series according to the classical definition remain divergent, all those already convergent remain convergent, some of those without a result become convergent. Would you say that the integral of the Dirichlet function diverges? Or is it more correct to say that it does not exist according to Rienmann and instead it exists according to Lebesgue?

  • @saharhaimyaccov4977
    @saharhaimyaccov4977 Месяц назад

    Where the video of this monster integral 😢🎉

  • @EHMM
    @EHMM Месяц назад +1

    W

  • @Why553-k5b_1
    @Why553-k5b_1 Месяц назад

    we need to stop him when it's not to early

  • @jatingoyal318
    @jatingoyal318 Месяц назад

    bro i am your biggest fan from india. please help your lil bro in solving triple submition ques