red integral black integral

red integral black integral
In this video, I solve an interesting integral as an infinite series. This is a sequel to the "black integral red integral" video, and is also featured on ‪@blackpenredpen‬'s channel, enjoy!
black integral red integral: • black integral red int...
Integrals Playlist: • Integrals
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Пікірлер: 97

  • @drpeyam
    @drpeyam2 жыл бұрын

    Happy birthday to me 🥰

  • @algorithminc.8850

    @algorithminc.8850

    2 жыл бұрын

    Definitely keep with age mentally and physically monotonically increasing ... cheers ...

  • @Ak-ly5qn

    @Ak-ly5qn

    2 жыл бұрын

    Happy birthday Dr Peyam.

  • @nicolasdiez4239

    @nicolasdiez4239

    2 жыл бұрын

    Happy Birthday, pro

  • @jacobzetterfeldt3652

    @jacobzetterfeldt3652

    2 жыл бұрын

    Happy birthday 🎂

  • @anushkrajbordia1873

    @anushkrajbordia1873

    2 жыл бұрын

    Happy Birthday Sir... May you have all the happiness in the world

  • @jonasdaverio9369
    @jonasdaverio93692 жыл бұрын

    That's a really cool one I think, I should suggest it to the calculus 1 teacher for whom I'm a teaching assistant.

  • @Ak-ly5qn
    @Ak-ly5qn2 жыл бұрын

    better if we use identity related to limits of integrals and then integrand will be 1/(1+cos(x)) then use cos(x)=2cos^2(x/2)-1 and finally integrand will be 1/(2cos^(x/2) ) which is derivative of tan(x/2) wrt x. under the limits answer will be 1

  • @patipateeke
    @patipateeke2 жыл бұрын

    Congrats Peyam! Have a really good day! And thx for the beautiful movie!

  • @mdrifaturrahman4443
    @mdrifaturrahman44432 жыл бұрын

    Alternative suggestion: The whole series can be written as a summation of (-sinx)^n from 0 to n. Switch the integral and sum, you get gamma function.

  • @gamingresumed1788

    @gamingresumed1788

    2 жыл бұрын

    It wouldnt be alternative sigh though

  • @erikkonstas

    @erikkonstas

    2 жыл бұрын

    Problem is, it's (-sinx)^n...

  • @mdrifaturrahman4443

    @mdrifaturrahman4443

    2 жыл бұрын

    Oh yeah I made a typo, thanks guys

  • @gokulanathmaheshkumar304
    @gokulanathmaheshkumar3042 жыл бұрын

    HAPPY BIRTHDAY VV WHOLESOME OF U TO DO A BLACK PEN RED PEN VIDEO ON UR BDAY. RLY SHOWS HOW GREAT U GUYS R

  • @marius3023
    @marius30232 жыл бұрын

    My man has got a golden rolex on... Love you Peyam

  • @Dalayah
    @Dalayah2 жыл бұрын

    happy birthday ! 🥳

  • @user-wu8yq1rb9t
    @user-wu8yq1rb9t2 жыл бұрын

    Hello Dear Dr Peyam. At first: *happy birthday 🎉 and Best Wishes* . And second: thank you for such an interesting math problem. I watched it and at the same time I learned and also laughed (for your jokes about party, bprp and ...) Thank you so much (again happy birthday)

  • @rezaetemad591
    @rezaetemad5912 жыл бұрын

    loved it...thanks

  • @mastershooter64
    @mastershooter642 жыл бұрын

    Happy birthday Dr.Peyam

  • @DrWeselcouch
    @DrWeselcouch2 жыл бұрын

    Here before aash! Happy Bday Dr. P!

  • @shyeyebee
    @shyeyebee2 жыл бұрын

    fascinating!

  • @shahinjahanlu2199
    @shahinjahanlu21992 жыл бұрын

    Happy birthday dr pyam

  • @gauravbharwan6377
    @gauravbharwan63772 жыл бұрын

    Loved it

  • @neelanshupanigrahi2553
    @neelanshupanigrahi25532 жыл бұрын

    you can substitute sin(x) with {(2tan(x/2))/(1+tan^2(x/2))} its quite simpler.

  • @mohamedabdelkareem9443
    @mohamedabdelkareem94432 жыл бұрын

    great integral great video

  • @brendanlawlor2214
    @brendanlawlor22142 жыл бұрын

    haha are you over 30 yet ?? Happy birthday Doc Your use of multiply top n bottom by 1-sine reminds me of the famous secant integral by Isaac Barrow , Newton's professor He multiplied sec by cos top n bottom then cos^2 bottom is 1-sin^2 then partial fractions , result the log ( 1-sin / 1+sin ). So , if Newton discovered calculus how come Barrow 1. used integral calculus before Newton was born 2. Barrow was the first to point out that differentiation and integration are inverses = the Fundamental Theorem of Calculus ? Turns out calculus discovered before Newton by dozens before Newton eg Fermat differentiation , Cavalieri integration both before Newton was born But Newton famous coz stunning application to Solar system Gravity Another beaudy Doc !! eres muy inteligente mi amigo jijijiji

  • @utilizator1701
    @utilizator17012 жыл бұрын

    For \int_0^{\pi/2} \frac1{1+sin(x)}dx I have used the substitution t=tan(x/2) and I did not have problem with improper primitive.

  • @pardeepgarg2640
    @pardeepgarg26402 жыл бұрын

    Happy Birthday Dr πyumh cake 🎂🎂

  • @utilizator1701
    @utilizator17012 жыл бұрын

    8:19 we are allowed to use L'Hospital rule in that case? I know that one of conditions for L'Hospital rule is the denominator function to not be 0 for x\in D\{x0}, where D is the domain definition of numerator and denominator functions, and x0 is the value which are we calculating the limit. In this example, cos(x)=0 for infinitly many points, not just for pi/2.

  • @PAWANKUMAR-km4sl
    @PAWANKUMAR-km4sl2 жыл бұрын

    Best sir

  • @mathunt1130
    @mathunt11302 жыл бұрын

    The sum of the series was trivially obvious as long as |sin(x)|

  • @ruxleec
    @ruxleec2 жыл бұрын

    Dr Peyam = The Party!!!

  • @tgx3529
    @tgx35292 жыл бұрын

    Happy Birthday, 1+sinx= sin(π/2)+sinx=2*sin(x/2 +π/4)*cos(x/2-π/4).After substitution y=x/2+π/4 we have integral 1/((siny)^2) dy where y go π/4 till π/2. We have then -(0-1)=1

  • @DarkMonolth
    @DarkMonolth2 жыл бұрын

    My first thought was to use the Wallis identity for powers of sin(x) from 0 to pi/2

  • @MrRyanroberson1
    @MrRyanroberson12 жыл бұрын

    what this really means is if you take the 1 out of the original integral, that all of those sine terms perfectly annihilate one another. most notably you can take all of the odd powers and move it to the other side to get: integral 0 to pi/2 of sum sin^(2n) dx = integral 0 to pi/2 of sum sin^(2n+1) dx. the left sum becomes: sum 1/(1-sin^2) - 1 = (some steps later) = tan^2 so we find an interesting expression for the integral of tan^2 in terms of an infinite integral of odd powers of sin(x), though since the first diverges, we know the second therefore also diverges.

  • @yassinetiaret505
    @yassinetiaret5052 жыл бұрын

    BlackPenRedPen Can hold it Hhhhh. The two of you are amazing, God bless you.❤️🌹

  • @AngadSingh-bv7vn
    @AngadSingh-bv7vn2 жыл бұрын

    the other video black integral red integral was filmed in the same shirt so probably filmed together but that video was released in dec 2020 and its sep 2021 now! what were you doing @Dr Peyam

  • @drpeyam

    @drpeyam

    2 жыл бұрын

    See description

  • @mathematics6199
    @mathematics61992 жыл бұрын

    Hey it is 1/(1+sinx) and further it is 1/(sin(x/2)+cos(x/2))^2 and further it can be reduced to 1/ cost^2 which is sect^2 ( by suitable substitution ofc) then it is much simpler right?

  • @mathematics6199

    @mathematics6199

    2 жыл бұрын

    Nevermind Actually I didn't see the solution , which is much better

  • @Vladimir_Pavlov

    @Vladimir_Pavlov

    2 жыл бұрын

    dx/(1+sinx)=dx/(cosx/2 +sinx/2)^2 =dx / [(cosx/2)^2*(1+tanx/2)^2] = = 2dy/y^2. Integration limits for the variable y: lower = 1 , upper =2. Is that what you meant?)

  • @vnever9078
    @vnever90782 жыл бұрын

    Hey Dr peyam can you do some International Math Olympiad problems

  • @vnever9078

    @vnever9078

    2 жыл бұрын

    It would be so helpful

  • @mathematics6199

    @mathematics6199

    2 жыл бұрын

    Hey could you please suggest some problems, I will do over my channel

  • @dr.rahulgupta7573
    @dr.rahulgupta75732 жыл бұрын

    Thanks for presenting a nice integral. Happy birthday to you Dr 3.14159.....m . My best wishes are always with you . Go ahead fearlessly.

  • @Observer_detector
    @Observer_detector2 жыл бұрын

    F(x)=2/(1+tan(x/2))+C ?

  • @iridium8562
    @iridium85622 жыл бұрын

    How did he integrate from 0 to π/2 when the infinite sum wouldn't converge if x=π/2?

  • @iridium8562

    @iridium8562

    2 жыл бұрын

    Oh he used the limit at the end, aight

  • @jarikosonen4079
    @jarikosonen40792 жыл бұрын

    What if you integrate from -π/2 to 0 ?

  • @adiaphoros6842

    @adiaphoros6842

    2 жыл бұрын

    Diverges, because the function has singularities at x = (4n-1)π/2

  • @polasz01
    @polasz012 жыл бұрын

    I like You! Greetings from Poland :D

  • @ajiwibowo8736
    @ajiwibowo87362 жыл бұрын

    But sin(π/2) is 1 so why we can do that? And note that the ratio is |r|

  • @drpeyam

    @drpeyam

    2 жыл бұрын

    Improper integral

  • @ajiwibowo8736

    @ajiwibowo8736

    2 жыл бұрын

    @@drpeyam oh yes forgot about that bite, thats why you use limit, so sorry Ln(1-Sinx)

  • @bezirksbesamer9309
    @bezirksbesamer93092 жыл бұрын

    I thought you speak austrian german in this video 😹

  • @Vladimir_Pavlov
    @Vladimir_Pavlov2 жыл бұрын

    Professor. you have a beautiful haircut !

  • @riazuddinsheikh3198
    @riazuddinsheikh31982 жыл бұрын

    But sinx can be equal to 1 in the interval. But for a geometric series it must be less than 1.

  • @drpeyam

    @drpeyam

    2 жыл бұрын

    That’s fine, improper integral

  • @determinantmatrix9584

    @determinantmatrix9584

    2 жыл бұрын

    sinx = x

  • @nikhilnagaria2672

    @nikhilnagaria2672

    2 жыл бұрын

    The point is more proven by the fact that the antiderivative is not defined at x=π/2 which is just sin(x)=1. Hence, you can view the given problem as lim(b->π/2)int from 0 to b ..... and then sin(x)

  • @kilian8250
    @kilian82502 жыл бұрын

    But it is an improper integral. At pi/2 the series you’re integrating is divergent.

  • @johnmelenasgarcia958
    @johnmelenasgarcia9582 жыл бұрын

    Be my teacher

  • @yoav613
    @yoav6132 жыл бұрын

    Another nice integral for your cool integrals playlist🤗

  • @neilgerace355
    @neilgerace3552 жыл бұрын

    2:29 Can we sue this doctor for malpractice ;)

  • @drpeyam

    @drpeyam

    2 жыл бұрын

    😂😂

  • @hahahasan
    @hahahasan2 жыл бұрын

    you could call l'hopital's rule the "loppy-lu" :)

  • @amirhoseinmeshkini9093
    @amirhoseinmeshkini90932 жыл бұрын

    nice shirt

  • @neilmccafferty7830
    @neilmccafferty78302 жыл бұрын

    error spotted

  • @drpeyam

    @drpeyam

    2 жыл бұрын

    Where?

  • @neilmccafferty7830

    @neilmccafferty7830

    2 жыл бұрын

    @@drpeyam belated apologies, I got my signs mixed up. second line where the square was taken out of the brackets.

  • @gaurav7582
    @gaurav75822 жыл бұрын

    Nice way to copy BPRP 😂😂😂😂

  • @alannolan3514
    @alannolan35142 жыл бұрын

    wtf