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Believe in double integral, NOT single integral 

blackpenredpen
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I know we haven't done a hard integral for a while now, so let's integrate ((1-e^(-t))/t)^2 from 0 to infinity. I didn't use Feynman's technique of integration for this since the denominator is t^2, but I used a double integral to solve this one! Surprised? Watch the video to find out my solution!
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23 сен 2024

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Комментарии : 88   
@blackpenredpen
@blackpenredpen 2 дня назад
Using Feynman's technique TWICE! (the integral of sin^3(x)/x^3 from 0 to inf) ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-weZLETAIDEk.htmlsi=rns_1h9G4MbG5oDS
@leonardobarrera2816
@leonardobarrera2816 День назад
dude Your photo... =(
@leonardobarrera2816
@leonardobarrera2816 День назад
I like the one with 2 markets =(
@leonardobarrera2816
@leonardobarrera2816 День назад
Awoms video Also
@aniruddhaghosh1303
@aniruddhaghosh1303 2 дня назад
I do see all of your videos from India. I'm 63 year old. Whenever I see your video I always feel sorry for that I didn't get a teacher like you in my yearly life. You are such rare class of teacher who can make the learning fun and enjoyable.
@blackpenredpen
@blackpenredpen 2 дня назад
Thank you so much for you nice comment! I am very happy to hear this!
@aniruddhaghosh1303
@aniruddhaghosh1303 2 дня назад
Will you please make a video to find the coordinates of the points of intersection of two intersecting circles.
@leonardobarrera2816
@leonardobarrera2816 День назад
@@aniruddhaghosh1303 thar is a nice tho Mmmm, well, a clue that I can give you is that, don't think on a function world accepted by school Just, plug the same varibles and use the quadratic formula for find out y [f(x)] That is something that works out
@junkgum
@junkgum 16 часов назад
Distance formula at certain coordinates?
@leonardobarrera2816
@leonardobarrera2816 12 часов назад
@@junkgum mmm Sqrt[(y2-y1)^2+(x2-x1)^2] If I am not bad
@yuri117_br
@yuri117_br 2 дня назад
BPRP please never stop posting you are the GOAT
@blackpenredpen
@blackpenredpen День назад
Thanks!
@AlokPatil-sz7er
@AlokPatil-sz7er День назад
Love you bro
@cdkw2
@cdkw2 2 дня назад
Hey bprp I am hosting a Integration Bee in my school and I included many integrals from your 100 integrals, so glad that you provide such good resources!
@blackpenredpen
@blackpenredpen 2 дня назад
Glad to help!! 😃
@umylten4142
@umylten4142 День назад
Feynman's technique works fine. I set up I(x) = the same integral where the integrand is multiplied by exp(-xt). Take the second derivative which is easy to find (just a bunch of exponentials to integrate), and then using that I''(x), I'(x) and I(x) approach 0 when x goes to infinity, you can find I(x) by integrating twice. If I didn't mess up, you get: I(x) = x•ln[x(x+2)/(x+1)²] + 2ln[(x+2)/(x+1)] which leads to the expected result I(0) = 2ln(2) = ln(4) (technically that final calculation is a limit calculation because of the first term, but it works fine).
@Happy_Abe
@Happy_Abe 2 дня назад
In general we can’t always use Fubini so some justification in that step is required
@alphazero339
@alphazero339 День назад
What exactly would I have to prove here to be able to use it
@Happy_Abe
@Happy_Abe День назад
@@alphazero339you’d have to prove(or already know) that the function f(x,y) is integrable in the product measure space. Meaning that when you integrate |f(x,y)| over XxY with respect to the product measure on XxY(these things have to be properly defined using measure theory), then this gives a finite value. Then we can take the integral of f(x,y) (without absolute values) over the product measure space and evaluate it as a double integral and exchange the order in which we integrate. In practice, we can more easily use Tonelli’s theorem here: If f(x,y) is non-negative and measurable then we always have this equality, but the integrals may not be finite. In the video’s case, the exponential function is always non-negative and is measurable so this works and no need to even verify Fubini!
@paya4030
@paya4030 День назад
This channel has mostly everything one could need for calculus I to III
@allmight801
@allmight801 День назад
Finally my guy does hard stuff again. Would love to see some complex integration stuff via Residue Theorem.
@Intu_369
@Intu_369 День назад
Wow I've suffered to solve this question but you really did it with the simplest way. Great 👍❤
@IoT_
@IoT_ 2 дня назад
I think, first time I saw "reverse Feynman/Leibniz's rule" on the channel of Michael Penn. That's a very nice approach 👍🏽
@klerulo
@klerulo День назад
Bprp: This integral is hard. To solve it, I'm going to make it WAY more intimidating first.
@redrosin99
@redrosin99 День назад
So nice to recall my undergraduate calculus classes. I studied at the Technion, Israel and you are certainly on the level to teach there. Thank you so much for your wonderful explanations!
@rockstarayan1959
@rockstarayan1959 2 дня назад
You are the best mathematician 🎉
@ДанилоФилонов
@ДанилоФилонов День назад
I love math, especially when such beautiful puzzles and solutions came out, that's just gorgeous, so beautiful and awesome, Please never stop seeking for such brilliants of math, that is indeed joyful thing)
@dudl2945
@dudl2945 День назад
The kind of smile I had watching this video probably can't be achieved by any other entertainment thing in this world. What a nice way to solve it
@tambuwalmathsclass
@tambuwalmathsclass День назад
Incredibly incredible ❤❤
@walidability
@walidability День назад
Actually this is a beautiful solve, I really enjoyed its simplicity.
@benjoshuayip2520
@benjoshuayip2520 День назад
Integrate by parts (differentiate the top, integrate the bottom) to get I = ∫ (-2e^-2t + 2e^-t)/t dt. Let x = e^-t to get I = 2 ∫[0,1] (x-1)/(lnx) dx, which can be solved by Feynman's.
@عَمرُبنوليدالمسلم
To use Feynman's technique you first need to Differentiate the numerator and Integrate the denominator using IBP, then use the technique on the resulting integral.
@6612770
@6612770 2 дня назад
Mind Blown
@Szynkaa
@Szynkaa 2 дня назад
lovely tricks
@stevemonkey6666
@stevemonkey6666 День назад
3 integral signs in a row😁👍
@neriya-bd
@neriya-bd День назад
lovely solution
@cdkw2
@cdkw2 2 дня назад
OMG new bprp pfp and video? Lets go!
@Mario_Altare
@Mario_Altare День назад
IBP twice and then Gamma function is your uncle (and your friend): I = -2 ∫_0^∞ [2e^(-2t)-e^(-t)] ln⁡ t dt = 2γ - 2 ln 2 ∫_0^ e^(-v)⁡ = 2 ln 2 = ln 4
@tommyliu7020
@tommyliu7020 23 минуты назад
Are you differentiating the numerator and integrating the denominator?
@Mario_Altare
@Mario_Altare 18 минут назад
@@tommyliu7020 Yes, I did a first IBP letting dv = 1/t^2 and u = [1-e^(-t)]^2; then I've repeated this procedure with the resulting integral, obtaining -2 ∫_0^∞ [2e^(-2t)-e^(-t)] ln⁡ t dt
@aniruddhaghosh1303
@aniruddhaghosh1303 День назад
Will you please make a video on how to get the coordinates of points of intersections of two intersecting circles. Thank you.
@TechnoBeats1251
@TechnoBeats1251 12 часов назад
Funny part is that Chat-GBT says that the solution is Pi^2/6 , i'm never asking him about integrals again.
@sovietwizard1620
@sovietwizard1620 День назад
I solved the indefinite integral normally by expanding it out and got the 3 normal integrals by itself and they were actually quite easy to solve. You get a slightly complicated expression involving Ei function. I did it this way to simplify it, but when I took the limit from zero to infinity, the infinity part became 0 and the other zero part was quite tricky as I had to solve for lim as t->0 of 2Ei(-t)-2Ei(-2t), I had absolutely o idea how to do this as this was in the form infinity - infinity indeterminate. I used wolfram alpha and apparently it was -ln4, but I'm still pretty confused lol.
@yurfwendforju
@yurfwendforju День назад
10nth grader from germany here. First intuition is to do DI w/ (1-e^-t) , 1/t^2
@alphazero339
@alphazero339 День назад
Why are you telling your grade
@sadi_supercell2132
@sadi_supercell2132 День назад
Integration by parts , integrate 1 over t^2 differentiate numerator , after that feynman trick works
@fdileo
@fdileo День назад
Can you use the Fubini Tonelli's Theorem at 6:04?
@kristopherwilson506
@kristopherwilson506 День назад
Yes, as the function is nonnegative and measurable, and the exponential function is nonnegative
@MatrixMultiplication
@MatrixMultiplication 9 часов назад
Please upload all your content to RUMBLE
@RoyalYoutube_PRO
@RoyalYoutube_PRO День назад
Can't you just use Gamma Integral after opening the bracket and splitting the numerator??
@holyshit922
@holyshit922 День назад
I would start with integration by parts Then maybe Laplace transform
@holyshit922
@holyshit922 День назад
Integration by parts gives me 2\int_{0}^{\infty}\frac{(1-exp(-t))exp(-t)}{t}dt Integrand and interval of integration hints me to use Laplace transform so i calculate Laplace transform L((1-exp(-t))/t) plug in s = 1 and double the result To calculate L((1-exp(-t))/t) it is enough to calculate L(1-exp(-t)) and integrate the result
@Patapom3
@Patapom3 День назад
Amazing!
@namangoyal1297
@namangoyal1297 2 дня назад
Cant we write this in the form of Exponential integral and the Gamma function?
@nuclearrambo3167
@nuclearrambo3167 День назад
I think properies of laplace transform or residue theorem can be used
@UnTipoSinNombre
@UnTipoSinNombre 8 часов назад
VERY NICE
@HiddenKey_210
@HiddenKey_210 15 часов назад
Triple integration is the bestest!
@danielntoko2117
@danielntoko2117 День назад
Very easy to solve!
@namangoyal1297
@namangoyal1297 2 дня назад
Pls make a video on the Product integral and The Riemann Zeta function
@aashishkumar9658
@aashishkumar9658 2 дня назад
That's a brilliant approach 😳
@Nain115
@Nain115 День назад
I just did it in ChatGPT, and it says that the answer is (pi²)/6 I told it that in bprp's video the answer was ln4, but GPT said that ln4 is the answer for the initial integral but without the square in the exponent
@OpPhilo03
@OpPhilo03 16 часов назад
Which marker you use?! Please tell me us sir
@davidbrisbane7206
@davidbrisbane7206 2 дня назад
The answer is nearly always ln(4) 😂
@bjornfeuerbacher5514
@bjornfeuerbacher5514 День назад
Only in the cases when it's not pi²/6 or the Euler Mascheroni constant. ;)
@davidbrisbane7206
@davidbrisbane7206 День назад
@@bjornfeuerbacher5514 Indeed.
@rauladrianbringasjimenez8656
@rauladrianbringasjimenez8656 23 часа назад
5:15 I didn’t understand, what theorem I’m missing?
@weishanlei8682
@weishanlei8682 2 дня назад
I am sure that this easy question can be solved bey o1 within 30 seconds.
@scottleung9587
@scottleung9587 День назад
Cool!
@perost1227
@perost1227 22 часа назад
Are x and y greater than 0?
@blackpenredpen
@blackpenredpen 16 часов назад
Yes bc those integrals go from 0 to 1
@perost1227
@perost1227 14 часов назад
@@blackpenredpen ahaaaa tyyy
@Silvar55x
@Silvar55x День назад
There's been some crackling on the mic in all the latest videos.
@blackpenredpen
@blackpenredpen День назад
Could you please provide me the time stamps? Thanks.
@Silvar55x
@Silvar55x День назад
@@blackpenredpen It's pretty common occurance. Just in this video: 0:00 - 0:05 about 7 times 0:14 single one 0:33 single one 0:48 - 0:50 a couple And so on. It sometimes seems to correspond to movements of the mic, like the slight upward hand movement at 0:05. Could be a faulty connection or frayed wire.
@blackpenredpen
@blackpenredpen День назад
Thank you so much for pointing those out! I will see what I can do to fix it!
@toeknee3900
@toeknee3900 День назад
New pfp!
@user-mf7li2eb1o
@user-mf7li2eb1o День назад
Im not even gonna try😂😂 Taking calc 1 rn
@ValidatingUsername
@ValidatingUsername 14 часов назад
Let t = x for mental simplicity sake and dt = dx.
@matei_woold_wewu
@matei_woold_wewu 12 часов назад
Rip old pfp of bprp
@kyriakoskourkoulis1159
@kyriakoskourkoulis1159 2 дня назад
Bro hellped me get through high school, next stop: college⚡💪
@kift.
@kift. День назад
eZ.
@ikerluqup5661
@ikerluqup5661 День назад
Lol😊
@rehanalam3900
@rehanalam3900 2 дня назад
First viewer
@stonecrane167
@stonecrane167 День назад
This is too easy
@keymind117
@keymind117 2 дня назад
lobter 🦞
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