Welcome! This is a math channel dedicated to mini courses, playlists and RANDOM stuff from various math subjects. Focus will be Calculus, Algebra, Number Theory and more.
Hi. Is that a book? I know a few books from Vikas Gupta
@adandap12 сағат бұрын
Ah... my previous comment was made too early. 😂
@owl3math2 сағат бұрын
🤣 yes I figured this was what you were referring to :)
@owl3math16 сағат бұрын
Here's the video with the other method: kzread.info/dash/bejne/i3h8l6V8Yb3Mkdo.html
@nezby394519 сағат бұрын
Wow you’re awesome! Perfect explanation I always thought mit bee integrals are waaay too difficult for me, but this problem is pretty nice. Will you be making a video about integrating using partial fractions? I can never integrate more difficult problems when partial fractions are involved. Still thank you for this awesome video!
@owl3math18 сағат бұрын
Hey Nezby. Thanks! I’ve done some videos on partial fractions before. Have you watched my other channel “Owls School of Math”? I think there’s quite a few over there but let me know if you need some help finding it
@owl3math18 сағат бұрын
youtube.com/@owlsschoolofmath9732
@iehudimКүн бұрын
makes me sad
@owl3math20 сағат бұрын
Hello. This problem makes you sad?
@iehudim20 сағат бұрын
@@owl3math Sad because i dont know How to solve It, till now
@owl3math16 сағат бұрын
@@iehudim ok good news! :)
@usualhacker2584Күн бұрын
in india we use this standard equation if integral a to b f(x) + integral f(a) to f(b) f inverse (x) is given then the answer is bf(b)-af(a)
@owl3mathКүн бұрын
Oh that’s interesting. Don’t think I’ve seen the formula like that before. 👍 thanks
@user-lg6fq1yt4g2 күн бұрын
Could, we solve this problem by using integration?
@owl3mathКүн бұрын
For the series convergence yes you can use the integral test here. But that does not provide an exact solution to the series
@user-lg6fq1yt4gКүн бұрын
@@owl3math 🙏🏽🙌🏽
@felipefred12792 күн бұрын
I really don’t remember those hyperbolic identities
@owl3mathКүн бұрын
Right! Many people have this issue. Use my trig cheat sheet! owlsmath.neocities.org/Trig%20Identities%20and%20Formulas/trig%20identities Free plug for me 😄
Beta function is so funny because every video that uses it is using a different representation each time
@owl3math4 күн бұрын
That’s true! 4 or more formulas for the same thing makes it hard to remember
@theupson4 күн бұрын
u= 2019(t^-2)/4 is a higher-odds thing to try- you can easily see it will give you a gamma integral, whereas your downfield vision has to be much sharper to see OPs approach will yield the gaussian integral- as opposed to something similar but intractable.
@owl3math4 күн бұрын
ooooh interesting!
@hemavathirajesh80124 күн бұрын
The integral is very good, but i tried to do by parts, by which i got 0. Nonetheless, thanks for the good integral !!
@owl3math4 күн бұрын
Nice thanks!
@felipefred12795 күн бұрын
You make it so simple
@owl3math4 күн бұрын
Thanks Felipe!
@adandap5 күн бұрын
Cool. I wouldn't have thought to do that. My solution was to write it as Re[ Int( x e^(- x (1 - i) ) dx)] and then IBP is easier.
@owl3math5 күн бұрын
Ah complex method is nice here. Then it’s just like the IBP of 2 things 👍
@VeteranVandal3 күн бұрын
The method I thought was this plus the Feynman trick.
@dkravitz785 күн бұрын
What you could have done instead is Feynman's trick, you end up doing almost exactly the same calculation but it is less rules/machinery. Set F(s) = integral ( exp(-sx) cos(x) , x=0..infinity) and assume s>0. F'(s) = - integral( x exp(-sx) cos(x) ) and so we want F'(1) F(s) is an easier integral, it is 1/(s^2+1) times exp(-sx) times (sin(x) - s*cos(x) ) From x=0 to x=infinity (assuming s>0) gives -s/(s^2+1) Derivative of this with respect to s is F'(s) = (s^2-1) / (s^2+1)^2 And so we quickly see F'(1)=0. Similar to your path but less "rules" needed.
@owl3math5 күн бұрын
Nice! Yep Feynman works nice here👍👍
@MikeT101015 күн бұрын
Nice job!...and...it's ZERO! ; )
@owl3math5 күн бұрын
Good timing Mike! You posted like just as I was switching pages and it popped right up 🤣
@antoinehedin66085 күн бұрын
Maybe a little bit more efficient than the classical way I initially chose, implying 4 consecutive IBP ^^.
@owl3math5 күн бұрын
Yes I did one previously like that and it’s fine but it’s a lot of IBP! 😂
@koennako21955 күн бұрын
You could also do this one without doing L transform, but I hate it. Mine aswell start memorizing L transform if I want to do these competition integrals.
@owl3math5 күн бұрын
I guess if it were an indefinite integral we’re forced into the IBP but I do like to avoid it in this case where we have 3 things. 👍
@MartinPerez-oz1nk5 күн бұрын
EXCELLENT !!!!!
@owl3math5 күн бұрын
Thanks Martin! 🙏😀
@theupson5 күн бұрын
im sorry, you handled this pretty clumsily. from 3:14 (and for petes sake the evenness symmetry doesn't take so much explanation), you should partition it along the integers. THEN you use the sub u = pi (x-n). that gets you to a better place than 9:39 in the video in 2 easy steps, given that |sin(x)| has period pi that recurring crappy integral e^x*sin(x)... never fricking humor your math prof by using integration by parts. e^x*sin(x) = im e^((i+i)*x), fast clean and painless.
@felipefred12796 күн бұрын
I am trying to find a video in that you use laplece to solve a mit integral. Do you remember which video is that?
@owl3math6 күн бұрын
There may be more than 1 but I did find this one in the Laplace transform playlist: kzread.info/dash/bejne/mophlZWync6vpM4.htmlsi=Ol2qEoyMlNrXjrE0
@felipefred12796 күн бұрын
@@owl3math is exactly this one, thanks. I wanted to show the technique to my differential equations professor
@owl3math5 күн бұрын
Oh interesting. Wonder what he says 😂
@adandap7 күн бұрын
I always liked this result. It easily generalises to L{t^n f(t)} as well.
@owl3math6 күн бұрын
Hi adandap. Right yes nth derivative and alternating sign. :)
@MikeT101017 күн бұрын
Laplace and differentiating under the integral sign...not bad! ; )
@owl3math7 күн бұрын
This is a fun one! 😃
@OwenChiu7 күн бұрын
What type of calc is this, i took calc ab and taking bc next year
@owl3math7 күн бұрын
Good question but not quite sure just because I don’t think they cover beta function or integral of inverses in integral calculus
@OwenChiu7 күн бұрын
cOol
@owl3math7 күн бұрын
Thanks!
@wasimohammad42807 күн бұрын
Just take out x from square root,then put 1/x=t,reduces to -Sin inverse 1/x,put the limit,get the answer-pi/6.
@maxgomez49098 күн бұрын
I like your videos
@owl3math8 күн бұрын
good to hear it! Thanks Max :)
@alexselby8028 күн бұрын
Just multiply by (1-sinx)/(1-sinx)
@owl3math8 күн бұрын
HI Alex. Yep, that's the method I mentioned early in the video. It's waaay way WAY faster that way :)
@henningkneller7 күн бұрын
how would you continue from there?
@owl3math7 күн бұрын
@@henningkneller Then you have 1- sin^2 x in the denominator which can be written as cos^2 x. Divide that into (1 - sin x) and split it into 2 integrals: sec^x and sec x tan x :)
@parthkalel67815 күн бұрын
@@owl3math when I do this I get the indefinite integral tanx - secx (+c) which is undefined at pi/2 so am I doing something wrong
@henningkneller5 күн бұрын
Clever! Thank you:)
@adandap9 күн бұрын
Who can go the distance? We'll find out in the long run...🎶
@owl3math8 күн бұрын
a lot of music references coming up! :) And nice use of music notes in the comment :)
@MikeT101019 күн бұрын
Take the long way home...
@owl3math9 күн бұрын
Yep 😀. I think that’s a song 😂
@owl3math8 күн бұрын
supertramp maybe
@MikeT101018 күн бұрын
@@owl3math You got it! kzread.info/dash/bejne/foSG1KqyiMbOdbw.html
@kaftan17769 күн бұрын
I like the power indices because in music 3/2 is a perfect 3rd and 2/3 is a perfect fourth.
@owl3math9 күн бұрын
Oooh. I didn’t know that 😀
@KevinAPamwar10 күн бұрын
Nice... Another solution Sin3y =3Siny-4Sin³y
@owl3math9 күн бұрын
Hi Kevin. So Use triple angle on Sin 6x = 3 sin 2x - 4 sin^3 2x? Makes sense...then its easy from there.
@KevinAPamwar10 күн бұрын
Nice... You can skip the 1st nine minutes... Sin^4x + Cos^4x = (Sin^2x + Cos^2x)^2 - 2*Sin^2x*Cos^2x= 1- 1/2 *(Sin^2(2*x))
@justabunga110 күн бұрын
The second method to do that is to let u=ln(x), so x=e^u. Then, dx=e^udu. When x=1, u=0. The limit as x goes to ∞, then u goes to ∞. The new limit of that integral should be the integral from e to ∞ of (e/3)^udu. That integration is evaluated from 0 to ∞ for the function (e/3)^u/ln(e/3). This means (e/3)^0/ln(e/3)=1/ln(e/3)=log_(e/3)(e). Note that the upper limit of integration will approach to 0. You can also look at the exponential function 1/(3^ln(x))=(1/3)^ln(x)=x^ln(1/3) and then you can go from there to integrate that function.
@owl3math9 күн бұрын
nice method! thanks :)
@dkravitz7810 күн бұрын
My philosophy is there's no reason not to at least start this way. It won't hurt.
@owl3math10 күн бұрын
Oooh this was kind of an interesting scenario. Kind of forgot about this one. :)
@Hypnotic.-.10 күн бұрын
You explained it so well that even me as a high school student could understand it 💀 I couldn’t repeat what you did but I wasn’t really confused at any point 😂
@owl3math10 күн бұрын
WOW thats great! I think i'm proud of both of us 😂
@takyc788310 күн бұрын
both methods so cool
@owl3math10 күн бұрын
THANKS! :)
@Arandomguy-bi1yl10 күн бұрын
Excellent method I haven't spent much time with beta function, I here know a very common one y=(1-x^3/2)^3/2 x=(1-y^2/3)^2/3 Just calculated the inverse function So (1-x^2/3)^2/3=F inverse x The integral of f-1(x) from 0 to 1 now, put x=f(u)=(1-u^3/2)^3/2, dx=f'(u)du The limit changes to 1 to 0, as there is a minus Infront of it we change it into positive by changing the limit The inverse integral changed into xf'(x) or uf'(u) after the transformation Now we if we take the whole integral f(x)+xf'(x) from 0 to 1, see the term in the integral is the derivative of xf(x) So the integration is xf(x) and after putting the values We get 1f(1)-0f(0)=0 f(1)=(1-1)^3/2=0 The result is 0 Oh I skipped the first part, it's actually the same thing
@owl3math10 күн бұрын
Yep it's the first method but still thanks for the nice explanation!
@DakshSinghRawat-kr7nw10 күн бұрын
Nice one tho
@owl3math10 күн бұрын
thanks!
@prakharjain544810 күн бұрын
B(f(b) - af(a) pretty standar identity tho its pretty hard striking when not dine something similar
@owl3math10 күн бұрын
Hi. What is that identity? Beta subtracting 2 functions?
@arzaseb10 күн бұрын
cool
@owl3math10 күн бұрын
thanks!
@adandap10 күн бұрын
Oh, I didn't know the variation on the beta function with the 'n' present. That's useful. I did a u sub in each term, u = x^(2/3) etc.
@owl3math10 күн бұрын
Nice. Yes, it's nice to have all the forms of beta but u-sub always gets it back to the more familiar form. :)
@s.hjb010 күн бұрын
bloody hell would never have thought of this
@owl3math10 күн бұрын
this situation with the Inverses doesn't come up all that often so don't feel too bad :)
@mangakhoon4517go10 күн бұрын
Cool
@owl3math10 күн бұрын
thanks!
@mangakhoon4517go10 күн бұрын
@@owl3math but I don't understand properly they didn't teach this in highschool
@booboobaloney10 күн бұрын
Very cool use of inverses!
@mhm642112 күн бұрын
80 * 6 - 60 * 24 + 14 * 120 - 720 just used gamma definition, no pen or paper
@owl3math12 күн бұрын
Great! That works nicely 👍👍👍
@owl3math12 күн бұрын
error correction: the formula I use for sinh at initially is incorrect and should be a/(s^2 - a^2) and therefore my formula for cosh is wrong as well and should be s/(s^2 - a^2). I'll work on a correction. Thanks for your patience. :)
@LCDL613 күн бұрын
Isn't the Laplace of sinh at=a/(s²-a²)? In the video it is a/(s²+a²), that changes the result of the Laplace of cosh
@owl3math12 күн бұрын
Yep you're right. Big mistake in this one! I'll look into making another video I think. I did have it correct in the sinh at video before it but then brought over the wrong value into this video for no particular reason.
@rwilson560113 күн бұрын
i genuinely look forward to these. ty
@owl3math12 күн бұрын
Glad to hear it! Thank you :)
@gesucristo013 күн бұрын
Just multiply the bracket to the exponential and you get the gamma function.
Пікірлер
this is in A DAS gupta
Hi. Is that a book? I know a few books from Vikas Gupta
Ah... my previous comment was made too early. 😂
🤣 yes I figured this was what you were referring to :)
Here's the video with the other method: kzread.info/dash/bejne/i3h8l6V8Yb3Mkdo.html
Wow you’re awesome! Perfect explanation I always thought mit bee integrals are waaay too difficult for me, but this problem is pretty nice. Will you be making a video about integrating using partial fractions? I can never integrate more difficult problems when partial fractions are involved. Still thank you for this awesome video!
Hey Nezby. Thanks! I’ve done some videos on partial fractions before. Have you watched my other channel “Owls School of Math”? I think there’s quite a few over there but let me know if you need some help finding it
youtube.com/@owlsschoolofmath9732
makes me sad
Hello. This problem makes you sad?
@@owl3math Sad because i dont know How to solve It, till now
@@iehudim ok good news! :)
in india we use this standard equation if integral a to b f(x) + integral f(a) to f(b) f inverse (x) is given then the answer is bf(b)-af(a)
Oh that’s interesting. Don’t think I’ve seen the formula like that before. 👍 thanks
Could, we solve this problem by using integration?
For the series convergence yes you can use the integral test here. But that does not provide an exact solution to the series
@@owl3math 🙏🏽🙌🏽
I really don’t remember those hyperbolic identities
Right! Many people have this issue. Use my trig cheat sheet! owlsmath.neocities.org/Trig%20Identities%20and%20Formulas/trig%20identities Free plug for me 😄
Alternate method video: kzread.info/dash/bejne/f4ap0qx8aaauZNI.html
Beta function is so funny because every video that uses it is using a different representation each time
That’s true! 4 or more formulas for the same thing makes it hard to remember
u= 2019(t^-2)/4 is a higher-odds thing to try- you can easily see it will give you a gamma integral, whereas your downfield vision has to be much sharper to see OPs approach will yield the gaussian integral- as opposed to something similar but intractable.
ooooh interesting!
The integral is very good, but i tried to do by parts, by which i got 0. Nonetheless, thanks for the good integral !!
Nice thanks!
You make it so simple
Thanks Felipe!
Cool. I wouldn't have thought to do that. My solution was to write it as Re[ Int( x e^(- x (1 - i) ) dx)] and then IBP is easier.
Ah complex method is nice here. Then it’s just like the IBP of 2 things 👍
The method I thought was this plus the Feynman trick.
What you could have done instead is Feynman's trick, you end up doing almost exactly the same calculation but it is less rules/machinery. Set F(s) = integral ( exp(-sx) cos(x) , x=0..infinity) and assume s>0. F'(s) = - integral( x exp(-sx) cos(x) ) and so we want F'(1) F(s) is an easier integral, it is 1/(s^2+1) times exp(-sx) times (sin(x) - s*cos(x) ) From x=0 to x=infinity (assuming s>0) gives -s/(s^2+1) Derivative of this with respect to s is F'(s) = (s^2-1) / (s^2+1)^2 And so we quickly see F'(1)=0. Similar to your path but less "rules" needed.
Nice! Yep Feynman works nice here👍👍
Nice job!...and...it's ZERO! ; )
Good timing Mike! You posted like just as I was switching pages and it popped right up 🤣
Maybe a little bit more efficient than the classical way I initially chose, implying 4 consecutive IBP ^^.
Yes I did one previously like that and it’s fine but it’s a lot of IBP! 😂
You could also do this one without doing L transform, but I hate it. Mine aswell start memorizing L transform if I want to do these competition integrals.
I guess if it were an indefinite integral we’re forced into the IBP but I do like to avoid it in this case where we have 3 things. 👍
EXCELLENT !!!!!
Thanks Martin! 🙏😀
im sorry, you handled this pretty clumsily. from 3:14 (and for petes sake the evenness symmetry doesn't take so much explanation), you should partition it along the integers. THEN you use the sub u = pi (x-n). that gets you to a better place than 9:39 in the video in 2 easy steps, given that |sin(x)| has period pi that recurring crappy integral e^x*sin(x)... never fricking humor your math prof by using integration by parts. e^x*sin(x) = im e^((i+i)*x), fast clean and painless.
I am trying to find a video in that you use laplece to solve a mit integral. Do you remember which video is that?
There may be more than 1 but I did find this one in the Laplace transform playlist: kzread.info/dash/bejne/mophlZWync6vpM4.htmlsi=Ol2qEoyMlNrXjrE0
@@owl3math is exactly this one, thanks. I wanted to show the technique to my differential equations professor
Oh interesting. Wonder what he says 😂
I always liked this result. It easily generalises to L{t^n f(t)} as well.
Hi adandap. Right yes nth derivative and alternating sign. :)
Laplace and differentiating under the integral sign...not bad! ; )
This is a fun one! 😃
What type of calc is this, i took calc ab and taking bc next year
Good question but not quite sure just because I don’t think they cover beta function or integral of inverses in integral calculus
cOol
Thanks!
Just take out x from square root,then put 1/x=t,reduces to -Sin inverse 1/x,put the limit,get the answer-pi/6.
I like your videos
good to hear it! Thanks Max :)
Just multiply by (1-sinx)/(1-sinx)
HI Alex. Yep, that's the method I mentioned early in the video. It's waaay way WAY faster that way :)
how would you continue from there?
@@henningkneller Then you have 1- sin^2 x in the denominator which can be written as cos^2 x. Divide that into (1 - sin x) and split it into 2 integrals: sec^x and sec x tan x :)
@@owl3math when I do this I get the indefinite integral tanx - secx (+c) which is undefined at pi/2 so am I doing something wrong
Clever! Thank you:)
Who can go the distance? We'll find out in the long run...🎶
a lot of music references coming up! :) And nice use of music notes in the comment :)
Take the long way home...
Yep 😀. I think that’s a song 😂
supertramp maybe
@@owl3math You got it! kzread.info/dash/bejne/foSG1KqyiMbOdbw.html
I like the power indices because in music 3/2 is a perfect 3rd and 2/3 is a perfect fourth.
Oooh. I didn’t know that 😀
Nice... Another solution Sin3y =3Siny-4Sin³y
Hi Kevin. So Use triple angle on Sin 6x = 3 sin 2x - 4 sin^3 2x? Makes sense...then its easy from there.
Nice... You can skip the 1st nine minutes... Sin^4x + Cos^4x = (Sin^2x + Cos^2x)^2 - 2*Sin^2x*Cos^2x= 1- 1/2 *(Sin^2(2*x))
The second method to do that is to let u=ln(x), so x=e^u. Then, dx=e^udu. When x=1, u=0. The limit as x goes to ∞, then u goes to ∞. The new limit of that integral should be the integral from e to ∞ of (e/3)^udu. That integration is evaluated from 0 to ∞ for the function (e/3)^u/ln(e/3). This means (e/3)^0/ln(e/3)=1/ln(e/3)=log_(e/3)(e). Note that the upper limit of integration will approach to 0. You can also look at the exponential function 1/(3^ln(x))=(1/3)^ln(x)=x^ln(1/3) and then you can go from there to integrate that function.
nice method! thanks :)
My philosophy is there's no reason not to at least start this way. It won't hurt.
Oooh this was kind of an interesting scenario. Kind of forgot about this one. :)
You explained it so well that even me as a high school student could understand it 💀 I couldn’t repeat what you did but I wasn’t really confused at any point 😂
WOW thats great! I think i'm proud of both of us 😂
both methods so cool
THANKS! :)
Excellent method I haven't spent much time with beta function, I here know a very common one y=(1-x^3/2)^3/2 x=(1-y^2/3)^2/3 Just calculated the inverse function So (1-x^2/3)^2/3=F inverse x The integral of f-1(x) from 0 to 1 now, put x=f(u)=(1-u^3/2)^3/2, dx=f'(u)du The limit changes to 1 to 0, as there is a minus Infront of it we change it into positive by changing the limit The inverse integral changed into xf'(x) or uf'(u) after the transformation Now we if we take the whole integral f(x)+xf'(x) from 0 to 1, see the term in the integral is the derivative of xf(x) So the integration is xf(x) and after putting the values We get 1f(1)-0f(0)=0 f(1)=(1-1)^3/2=0 The result is 0 Oh I skipped the first part, it's actually the same thing
Yep it's the first method but still thanks for the nice explanation!
Nice one tho
thanks!
B(f(b) - af(a) pretty standar identity tho its pretty hard striking when not dine something similar
Hi. What is that identity? Beta subtracting 2 functions?
cool
thanks!
Oh, I didn't know the variation on the beta function with the 'n' present. That's useful. I did a u sub in each term, u = x^(2/3) etc.
Nice. Yes, it's nice to have all the forms of beta but u-sub always gets it back to the more familiar form. :)
bloody hell would never have thought of this
this situation with the Inverses doesn't come up all that often so don't feel too bad :)
Cool
thanks!
@@owl3math but I don't understand properly they didn't teach this in highschool
Very cool use of inverses!
80 * 6 - 60 * 24 + 14 * 120 - 720 just used gamma definition, no pen or paper
Great! That works nicely 👍👍👍
error correction: the formula I use for sinh at initially is incorrect and should be a/(s^2 - a^2) and therefore my formula for cosh is wrong as well and should be s/(s^2 - a^2). I'll work on a correction. Thanks for your patience. :)
Isn't the Laplace of sinh at=a/(s²-a²)? In the video it is a/(s²+a²), that changes the result of the Laplace of cosh
Yep you're right. Big mistake in this one! I'll look into making another video I think. I did have it correct in the sinh at video before it but then brought over the wrong value into this video for no particular reason.
i genuinely look forward to these. ty
Glad to hear it! Thank you :)
Just multiply the bracket to the exponential and you get the gamma function.
Yep good method! 👍👍👍