MIT 2022 Finals #2
4:50
Күн бұрын
Easy Way vs Hard Way
6:06
14 күн бұрын
Shortcut!! MIT 2024 Quarterfinals#1-2
3:27
Another NICE solution using 2024
7:51
One Trick makes this go sooo FAST!
2:52
UK 2024 #13 (METHOD 2!)
16:19
Ай бұрын
this one is a total hairball
12:09
Is this IMPOSSIBLE???
5:08
Ай бұрын
I misjudged this one at first
5:54
is this INSANE???
3:56
Ай бұрын
Surprisingly quick & easy! :)
3:07
Does it converge???
4:15
Ай бұрын
A slightly alternative method
3:16
OVERKILL every series you find
7:56
Пікірлер
@nicogehren6566
@nicogehren6566 23 сағат бұрын
Good question
@owlsmath
@owlsmath 23 сағат бұрын
thanks Nico!
@slavinojunepri7648
@slavinojunepri7648 Күн бұрын
Excellent
@owlsmath
@owlsmath 23 сағат бұрын
Thanks! 🙏
@prollysine
@prollysine 3 күн бұрын
2^11*ln2=ln2*(x-11)*e^((x-11)*ln2) , 2^3*2^8*ln2=ln2*(x-11)*e^((x-11)*ln2) , 8*ln2*e^(8*ln2)=ln2*(x-11)*e^((x-11)*ln2) , 8*ln2=ln2*(x-11) , 8=x-11 , x=3 , test , 2^3+3=11 , W( 2^11*ln2)=~ 5.545175444 , ln2*(11-x)=~ 5.545175444 , x= -(5.545175444/ln2)+11 , x=3 ,
@maxvangulik1988
@maxvangulik1988 3 күн бұрын
2^x=11-x 1=(11-x)2^x 2^11•ln(2)=(11-x)ln(2)e^(11-x)ln(2) (11-x)ln(2)=ln(256) 11-x=log_2(256)=8 x=11-8=3
@slavinojunepri7648
@slavinojunepri7648 3 күн бұрын
Excellent
@owlsmath
@owlsmath 3 күн бұрын
thanks :)
@MikeMagTech
@MikeMagTech 3 күн бұрын
Nice job. That was slightly headachy, but not too bad ; )
@owlsmath
@owlsmath 3 күн бұрын
Yep! More headaches than guess and check for sure
@holyshit922
@holyshit922 3 күн бұрын
If you want integral to calculate try this \int \frac{x}{\sqrt{(x+2)^2+exp(x)}}dx Result should be x - 2ln(x+2+\sqrt{(x+2)^2+exp(x)})+C and it is quite interesting because programs like Mathematica or Wolfram alpha can't calculate it You can try this and record video about it
@owlsmath
@owlsmath 3 күн бұрын
Looks tough!
@holyshit922
@holyshit922 3 күн бұрын
@@owlsmath if you add zero , use linearity of integral and multiply by one you will see suitable substitution but the most interesting fact is that computer programs can't calculate it When you look at result this x suggest what kind of zero you should add and argument of ln suggest you what kind of one you should multiply
@holyshit922
@holyshit922 3 күн бұрын
x=3 is a solution but is it the only one
@HJ28_398
@HJ28_398 2 күн бұрын
I don't know the proper way to do it, but just doing some Desmosing, I've found that around 3.44983 - 7.89905i and 3.44983 + 7.89905i are two of these such answers, you are correct 👏👏.
@Cyrusislikeawsome
@Cyrusislikeawsome Күн бұрын
I guess proving it with the W function kinda helps that because you can see via the graph
@reaperskyfall6691
@reaperskyfall6691 4 күн бұрын
After seeing this my brain 🧠: please pull out calculator 100ms
@owlsmath
@owlsmath 3 күн бұрын
Is that 100 milliseconds? Your brain reacted fast!
@reaperskyfall6691
@reaperskyfall6691 3 күн бұрын
@@owlsmath no sir I mean cal-c type 100ms
@owlsmath
@owlsmath 3 күн бұрын
Oh I see!
@nizogos
@nizogos 4 күн бұрын
The x=3 solution is visible,after that you could move all the terms of your equation to one side and define a function.From there you could prove that the function is monotonous through its derivatives and thus x=3 is a unique solution
@owlsmath
@owlsmath 4 күн бұрын
yep makes sense!
@taterpun6211
@taterpun6211 3 күн бұрын
At least for real numbers. Lambert W function has infinite branches like logz
@owlsmath
@owlsmath 3 күн бұрын
@@taterpun6211 right always infinite number of complex solutions
@kirbo722
@kirbo722 4 күн бұрын
Wow. :0
@owlsmath
@owlsmath 4 күн бұрын
😁
@maxvangulik1988
@maxvangulik1988 5 күн бұрын
I=L{sin(3x)/x}|[s=2] L{f(t)/t}=int[s,♾️](L{f(t)})ds I=int[2,♾️](L{sin(3x)})ds L{sin(ax)}=a/(s^2+a^2) I=int[2,♾️](3/(s^2+9))ds I=(arctan(s/3))|[2,♾️] I=pi/2-arctan(2/3) I=arctan(3/2)
@owlsmath
@owlsmath 5 күн бұрын
thanks Max!
@reaperskyfall6691
@reaperskyfall6691 5 күн бұрын
Sir is there any method we can use Laplace in this
@owlsmath
@owlsmath 5 күн бұрын
Hi Skyfall. Other than Laplace you can use Feynmans trick on this one. Not sure I know another way with x in the denominator
@RealQinnMalloryu4
@RealQinnMalloryu4 5 күн бұрын
e^ ➖ 2x sin(3x)^2/(x)^2 =e^ ➖ 2x{sin*9x^2}/x^2=w^{In^s^n^x^dx^sin^s^n ➖9x^2/dx^s^n ➖ x^2In^s^n^x^dx^sin^s^n^ ➖ 9x^2/dx^s^n ➖ x^2}^w=w^{In^s^n^x^dx^sin^s^n ➖ 9x^4/dx^sins^n ➖ 9x^4In^s^n^x^dx^sin^s^n^dx^sin^s^n ➖ 9x^4/dx^sin^s^n ➖ 9x^4}^w=w^{In^s^n^x^dx^sin^s^n^ ➖ 3^2x^2^2/dx^sin^s^n ➖ 3^2x^2^2In^s^n^x^dx^sin^s^n ➖3^2x^2^2/dx^sin^s^n ➖ 3^2x^2^2}^w=w^{In^s^n^x^dx^sin^s^n ➖ 1^1x^1^1/dx^sin^s^n ➖ 1^1x1^1In^s^n^x^dx^sin^s^n^ ➖ 1^1x^1^1/dx^sin^s^n ➖ 3^1x1^2}^w=In^s^n^x^dx^sin^s^n ➖ 3x^2 (w^{In^s^n^x^dx^sin^s^n^➖ 3piIn^s^n^x^d^x^sin^s^n^x +2}^w).
@MikeMagTech
@MikeMagTech 5 күн бұрын
Nice work ; )
@owlsmath
@owlsmath 5 күн бұрын
thanks Mike!
@adandap
@adandap 5 күн бұрын
I Feynmanned this one instead, with e^(- ax) then did the Euler form of sin(3x). One thing I missed was the neat use of arctan(1/x) at the end - I like that.
@owlsmath
@owlsmath 5 күн бұрын
hey adandap. Nice you turned Feynman into a verb! thanks :)
@adandap
@adandap 5 күн бұрын
@@owlsmath Wait til you meet my mate 'Fractional Feynman'!
@owlsmath
@owlsmath 5 күн бұрын
@@adandap ha! Saw your email and I got scared when I saw your paper. 🤣
@holyshit922
@holyshit922 5 күн бұрын
I would use integration by parts u = sin^2(x) , dv = 1/x^2dx then use double angle formula sin(2x) = 2sin(x)cos(x) then we can use substitution t = 2x Finally calculate L(sin(t)/t) and plug in s =0
@owlsmath
@owlsmath 5 күн бұрын
Nice method. That gets around the messiness of using the L(f(t)/t) twice
@doronezri1043
@doronezri1043 5 күн бұрын
Excellent use of the fundamental properties of Laplace Transform 🍻
@owlsmath
@owlsmath 5 күн бұрын
Thanks Doron. Cheers! 🍻
@par22
@par22 5 күн бұрын
Could you do Lobachevsky's rule on this?
@owlsmath
@owlsmath 5 күн бұрын
Hi Par. I don’t think so unless you can manipulate it to a different form. The 3x in the sin function is no problem and easily fixed by substitution but the trouble is e^-2x is not even or pi periodic
@holyshit922
@holyshit922 5 күн бұрын
I would use Laplace transform
@par22
@par22 5 күн бұрын
@@owlsmath Ah ok, thanks!
@nathanmarchant-fh9uw
@nathanmarchant-fh9uw 5 күн бұрын
cool integral, tried to solve it myself but changing variable mid integration always throws me off a bit
@owlsmath
@owlsmath 5 күн бұрын
Hi Nathan. Thanks! 👍👍👍
@RealQinnMalloryu4
@RealQinnMalloryu4 6 күн бұрын
In^x^e^x(x)^2In^x^e^x/In^x^e^x{x+x ➖}+In^x^e^x{1+1 ➖}=x^2/In^x^e^x{x^2+2}w^{In^x^e^xdx^n ➖ 2/dx^2n ➖ 2In^x^e^xdx^ n ➖ 2/dx^2n ➖ 2}^w =w^{In^x^e^x^dx^2n ➖ 4/dx^2n ➖ 4In^x^e^x^dx^2n ➖ 4/dx^2n ➖ 4}^w=w^{In^x^e^x^dx^2n ➖ 2^2/dx^2n ➖ 2^2In^x^e^x^dx^2n ➖ 2^2/dx^2n ➖ 2^2}^w=w^{In^x^e^x^d^x^1n ➖ 1^1/dx^1 n ➖ 1^1In^x^e^x^dx^1n ➖ 1^1/dx^1n ➖ 1^2}^w=dx^1n ➖ 2 (w^{In^x^e^xdx^n ➖ 2piIn^x^e^x^dx^n+1}^w). i liked the video i watched enjoyed thank fir Laplace transformation method substituted.
@yasserboulanouar1289
@yasserboulanouar1289 6 күн бұрын
I haven't studied laplace transform so I'm wondering can you also do it with integration by part ( talking abt ue^-un)?
@owlsmath
@owlsmath 6 күн бұрын
Hi Yasser. Yes, you can. I derived the formulas in a previous video but the method is integration by parts. So just takes a little longer. If you're interested here's the playlist: kzbin.info/aero/PLOvxeHw2nLaySIKdV-QTjiGHHkOx0M_2-
@yasserboulanouar1289
@yasserboulanouar1289 6 күн бұрын
@owlsmath thanks ill check it out
@slavinojunepri7648
@slavinojunepri7648 7 күн бұрын
We could expand 1/(1+x) into a geometric without the exponential substitution to get the result.
@owlsmath
@owlsmath 7 күн бұрын
HI Slavino. Makes sense but would you need to do the substitution later? Or does the integral work ok without it?
@edmundwoolliams1240
@edmundwoolliams1240 7 күн бұрын
You'd need to make the same substitution again later, yeah
@holyshit922
@holyshit922 4 күн бұрын
@@owlsmath after geometric series expansion all we need to do is change the order of summation and integration then integration by parts And it seems that we will get Catalan constant as result
@owlsmath
@owlsmath 4 күн бұрын
@@holyshit922 interesting. Oh because with IBP d(ln x) = 1/x so when you integrate x^n it cancels. I better do it on paper :)
@doronezri1043
@doronezri1043 8 күн бұрын
Excellent! Two of my favorite techniques - geometric sum and Laplace🍻
@owlsmath
@owlsmath 8 күн бұрын
yep me too. Thanks!
@zechariahwilson9994
@zechariahwilson9994 7 күн бұрын
omg control theory LMFAOOOOO I LOVE THIS GAME
@owlsmath
@owlsmath 7 күн бұрын
@@zechariahwilson9994 whats going on?
@waarschijn
@waarschijn 8 күн бұрын
Nice, very similar to the one you did on owl3.
@owlsmath
@owlsmath 8 күн бұрын
oooh didn't think of that but yes. thanks :)
@dean532
@dean532 8 күн бұрын
This is something 🎉
@owlsmath
@owlsmath 8 күн бұрын
Hi Dean. Thanks!
@holyshit922
@holyshit922 8 күн бұрын
In my opinion the best way to calculate this integral is to factor out sqrt(5) from denominator of the integrand and use substitution sqrt(x^2+6x+8) = u - x But if we want result presented on video it would be better to use Euler substitution with roots of quadratic trinomial inside square roots
@sabil8172
@sabil8172 9 күн бұрын
nice solution, thank you very much
@owlsmath
@owlsmath 9 күн бұрын
Thanks! Good suggestion! :)
@slavinojunepri7648
@slavinojunepri7648 9 күн бұрын
Excellent
@owlsmath
@owlsmath 9 күн бұрын
hi Slavino. thanks!
@Hussain-px3fc
@Hussain-px3fc 9 күн бұрын
When the formula doesn’t work, does that necessarily mean the integral will diverge?
@owlsmath
@owlsmath 9 күн бұрын
Yes I think for every case where the formula doesn’t work the integral diverges
@doronezri1043
@doronezri1043 10 күн бұрын
Crazy substitution 👏👏👏 loved the reflection formula🍻
@owlsmath
@owlsmath 9 күн бұрын
Hi Doron! Thank you 🙏 appreciate it 😀🍻🍺
@nicogehren6566
@nicogehren6566 10 күн бұрын
Very interesting approach.
@owlsmath
@owlsmath 9 күн бұрын
Thanks Nico!
@renesperb
@renesperb 10 күн бұрын
It is not hard to see that any integral (from 0 to inf.) with integrand a^[-x^p] * x^q ,with a >1, p > 0, q > -1 can be expressed with the Gamma function .
@owlsmath
@owlsmath 10 күн бұрын
yep agree 👍
@Aristotle-p8n
@Aristotle-p8n 11 күн бұрын
The most underrated math channel on yt
@owlsmath
@owlsmath 11 күн бұрын
awesome thanks!!! I'll take it :)
@renesperb
@renesperb 11 күн бұрын
An elegant way to calculate this integral is to use Cauchy 's integral theorem, stating that the integral of f[z] over a closed path P in the complex plane vanishes if P does not enclose any singularities of f[z]. We write the integral as Re[1/2 ∫exp[-x^2]*exp[i x]]=1/2*Re [exp[-(x- i/2]]*exp[-1/4],and the integration is from -inf. to + inf. Take f[z] = exp[-z^2] and consider a rectangular path in C : P1 = {- N < z = x < n} ,P2 = {z = N+i*y ,(0< y < 1/2)}, P3 = {z = i/2 +x ,(N > x > -N)}, P4 = {z = - N +i *y ,( 1/2 > y > 0 ) . If we let N -> inf. ,then it easy to show that the integrals along P2 and P4 vanish. On P1 we have ∫exp[-x^2 ] =√π , on P3 we have - integral we want to calculate . Since f[z] does not enclose any singularities the sum of our remaining integrals is zero , this means that the integral = 1/2 *√π *exp[ -1/4]
@owlsmath
@owlsmath 11 күн бұрын
Thanks!
@AscendantPerfection
@AscendantPerfection 11 күн бұрын
Beautiful 🥰🥰
@owlsmath
@owlsmath 11 күн бұрын
Thanks! 🙏
@schweinehundbullshit9176
@schweinehundbullshit9176 11 күн бұрын
You ruin anything good in your video with your way of speaking.
@schweinehundbullshit9176
@schweinehundbullshit9176 11 күн бұрын
Speak clearly. You mumble with your tongue and your hand.
@KentaEvans
@KentaEvans 11 күн бұрын
As an engineer point of view, you could consider e=3 and proceed from there to have e^(-x^3) for an approximated result. Nice video.
@owlsmath
@owlsmath 11 күн бұрын
Makes sense! Didn’t even think about that being close to 3. Thanks!
@pedromuniz3186
@pedromuniz3186 12 күн бұрын
Not satisfied with that solution
@owlsmath
@owlsmath 12 күн бұрын
Hi Pedro. What’s up? Was there a mistake?
@MikeMagTech
@MikeMagTech 12 күн бұрын
@@owlsmath I went back and reviewed it and I am satisfied that it is correct.
@owlsmath
@owlsmath 11 күн бұрын
@@MikeMagTechthanks for verifying it 👍
@MikeMagTech
@MikeMagTech 12 күн бұрын
Great job! ; )
@owlsmath
@owlsmath 12 күн бұрын
Thanks Mike! 🙏🙏🙏
@doronezri1043
@doronezri1043 12 күн бұрын
Excellent 🍻
@owlsmath
@owlsmath 12 күн бұрын
Thanks Doron! Cheers! 🍻
@saidchaida5431
@saidchaida5431 12 күн бұрын
Thanks for sharing!
@owlsmath
@owlsmath 12 күн бұрын
Thank you! 😊
@nicogehren6566
@nicogehren6566 13 күн бұрын
Lobachvsky saved us.
@owlsmath
@owlsmath 12 күн бұрын
yep! happens quite often :) thanks
@doronezri1043
@doronezri1043 13 күн бұрын
Yes! Definitely Lobachevsky's 🍻
@owlsmath
@owlsmath 13 күн бұрын
Yep thanks! 🍻
@holyshit922
@holyshit922 13 күн бұрын
Лобачевский and you read this name wrong Why I insist that you should read it correctly , because others repeat your wrong pronunciation
@doronezri1043
@doronezri1043 13 күн бұрын
@@holyshit922 Just checked and "Nikolai Lobachevsky" is the English version in Wikipedia (and others). What would you suggest (in English)?
@holyshit922
@holyshit922 13 күн бұрын
@@doronezri1043 It would be the best if you listen carefuly their pronunciation and try to repeat it In fact we in Poland had the same phone as it is present in this name (Ł) but it was simplified and today Poles pronounce ł a little bit different that л should be pronounced If I were born at least 10 years earlier I could write more about it
@reaperskyfall6691
@reaperskyfall6691 13 күн бұрын
Huff pray to God hope i don't want to face infinity problems type in my exams
@owlsmath
@owlsmath 13 күн бұрын
Hi Skyfall. Can you look at some past exams? I know some tests include these much more than others
@reaperskyfall6691
@reaperskyfall6691 15 күн бұрын
We can also use many alternatives for this
@owlsmath
@owlsmath 14 күн бұрын
Good point! I think there is many ways to do this one :) thanks
@slavinojunepri7648
@slavinojunepri7648 15 күн бұрын
Fantastic
@owlsmath
@owlsmath 14 күн бұрын
Thanks! 🙏🎉
@slavinojunepri7648
@slavinojunepri7648 15 күн бұрын
This integral is challenging without the lnx substitution and the cancellations.
@owlsmath
@owlsmath 14 күн бұрын
Hi Slavino. Yes true!
@slavinojunepri7648
@slavinojunepri7648 15 күн бұрын
Excellent
@owlsmath
@owlsmath 14 күн бұрын
thanks!