Local Extrema, Critical Points, & Saddle Points of Multivariable Functions - Calculus 3

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  • Опубликовано: 5 ноя 2019
  • This calculus 3 video explains how to find local extreme values such as local maxima and local minima as well as how to identify any critical points and saddle points in a multivariable function such as f(x,y).
    Lines & Planes - Intersection:
    • How To Find The Point ...
    Angle Between Two Planes:
    • How To Find The Angle ...
    Distance Between Point and Plane:
    • How To Find The Distan...
    Chain Rule - Partial Derivatives:
    • Chain Rule With Partia...
    Implicit Partial Differentiation:
    • Implicit Differentiati...
    ________________________________
    Directional Derivatives:
    • How To Find The Direct...
    Limits of Multivariable Functions:
    • Limits of Multivariabl...
    Double Integrals:
    • Double Integrals
    Local Extrema & Critical Points:
    • Local Extrema, Critica...
    Absolute Extrema - Max & Min:
    • Absolute Maximum and M...
    ________________________________
    Lagrange Multipliers:
    • Lagrange Multipliers
    Triple Integrals:
    • Triple Integrals - Cal...
    2nd Order - Differential Equations:
    • Second Order Linear Di...
    Undetermined Coefficients:
    • Method of Undetermined...
    Variation of Parameters:
    • Variation of Parameter...
    ________________________________
    Final Exams and Video Playlists:
    www.video-tutor.net/
    Full-Length Videos and Worksheets:
    / collections

Комментарии • 358

  • @TheOrganicChemistryTutor
    @TheOrganicChemistryTutor  6 месяцев назад +5

    Final Exams and Video Playlists: www.video-tutor.net/

  • @yaxsilanroy5951
    @yaxsilanroy5951 4 года назад +2346

    Fxx=-6 ; Therefore it is local maximum as Fxx

  • @chamba149
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    • @aswininaidu
      @aswininaidu Год назад +1

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    • @t.f.r287
      @t.f.r287 8 месяцев назад

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  • @gl291000
    @gl291000 4 года назад +124

    For problem one it should be local max. D < 0 and fxx(a,b) < 0 , then f(a,b) is a local maximum.

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  • @mrtom-a-hawk6732
    @mrtom-a-hawk6732 2 года назад +47

    How do you find the points of interest though? When your partials have both x and y in them, I mean

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    @CraftReaper-OmarFaruqTawsif 4 года назад +8

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    @tumelolebepe7258 2 года назад +20

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  • @keldonchase4492
    @keldonchase4492 4 года назад +236

    Shouldn't (2,2) be a local maximum? Since fxx is negative?

    • @pjk7685
      @pjk7685 4 года назад +12

      are the other examples correct? I dont want to study incorrect material....

    • @keldonchase4492
      @keldonchase4492 4 года назад +8

      @@pjk7685 I believe so.

    • @firdauspuzi1145
      @firdauspuzi1145 4 года назад +9

      Yeah thats correct

    • @luisvictoria
      @luisvictoria 2 года назад +10

      ​@@pjk7685 Yes, the other examples are correct. Notice how he contradicted himself later saying that fxxfyy - fxy > 0 meaning that it's a local min (which it is).
      Only the first example is incorrect.

    • @aadiliqbalkhan8216
      @aadiliqbalkhan8216 Год назад +4

      @@pjk7685 He may make a silly mistake while solving as any other human but he never teaches anything wrong and never will.

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    @DefiantPlayz 3 года назад +7

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  • @georgesadler7830
    @georgesadler7830 Год назад +3

    Professor Organic Chemistry Tutor, this is another fantastic video/lecture on Local Extrema, Critical and Saddle Points in Calculus Three/Multivariable Calculus. The problems associated with this topic are messy/problematic from start to finish. Once again, thanks to the great viewers for finding and correcting the error at the 6:04-minute mark in the video.

  • @imanichristian523
    @imanichristian523 Год назад +7

    im not gonna lie, math been having me fight for my life in the arena for the last couple weeks. thank u so much for this video. gonna secure atleast B because of your help. u a real one.

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    @tuguldurr 4 года назад +41

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    @TheLifeOfMarcus 2 года назад +1

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    @edrq89 4 года назад +10

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    @abhayhere15 3 года назад +2

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  • @johnathantran1101
    @johnathantran1101 2 года назад +7

    how did he find those three points at the last problem (14:34) (0,0) (1,1)(-1,1) . I know that he said plug in 0 ,1,-1 but I'm not sure why he did that.And where did he get those values to plug in

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    @Anna-qp1fi 2 года назад +4

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  • @raa2869
    @raa2869 4 года назад +92

    the point (2,2) should be a local maximum because fxx is negative and D is positive!

  • @ochiroo5077
    @ochiroo5077 4 года назад +49

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  • @ammarsohail633
    @ammarsohail633 2 года назад +1

    Great and helpful video. Thanks. Keep the good work up.

  • @memorynkhoma7964
    @memorynkhoma7964 Год назад +30

    on the second question, how did you determine that those were the points of interest?

    • @jessebrn30
      @jessebrn30 8 месяцев назад +1

      this

    • @khiziiikhan
      @khiziiikhan 2 месяца назад +1

      You first solve the two first partial derivative equations then you will find critical points from there

    • @borrobarra7935
      @borrobarra7935 2 месяца назад +1

      @@khiziiikhan how

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    @ObeyGoodness_20 2 года назад

    U are still the best educative RUclips even at this unconscious mistake...

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    @astartesfanboy5294 2 года назад +4

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    @carlmcgrath484 2 года назад +1

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    @parindyaherath4685 Год назад

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    @Shiiies 3 года назад

    really helped for my assignment thanks a bunch

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    @hemadlawar8350 2 года назад

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    @PatriciaMcAll 4 года назад +8

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  • @Ragehunter
    @Ragehunter Год назад

    2:25 yo that's actually helpfull thx, now I can imagine what's the local min, local max, saddle point! thank you again :)

  • @raccoonmath1828
    @raccoonmath1828 4 месяца назад

    Thank you soo much!

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    @rem6581 4 года назад

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  • @jayroldasuncion9236
    @jayroldasuncion9236 3 года назад +1

    @The Organic Chemistry Tutor, I think the example number 1, the point is a local maximum.

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    @amymsims 2 года назад

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    @Lmarfu725 2 года назад

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  • @Rems766
    @Rems766 3 года назад

    Once again, thanks !

  • @rami8896
    @rami8896 4 года назад +22

    If you could do triple integrals with finding the bounds, youll be a life saver

  • @user-cx1fy5yd3j
    @user-cx1fy5yd3j 2 месяца назад

    Thank you sir.

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    i dont usually write comments.....but i had to thank you....keep doing this

  • @landofmyth221
    @landofmyth221 4 года назад

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    @kylepodgorski9996 Год назад

    I love this man

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    @NhiHuynh-rz5ev 7 месяцев назад

    I learned more from you than from the lectures of my professor.

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    @rsidmmmdova642 Год назад +1

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    @welovebeauty509 2 года назад

    You are the best ❤

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    @asif7240 Год назад +1

    Thank you

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    @zamamfarhat8986 2 года назад

    Thanks man!

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    @kawsarahmedbadhon 4 года назад

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    @lazmerejesmin309 Год назад

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  • @calmz2343
    @calmz2343 4 года назад +8

    Could you do a video on sketching double and triple integrals?

  • @anshrastogi9883
    @anshrastogi9883 4 года назад

    Thank you sir😘😘

  • @mohammedabdlkider1286
    @mohammedabdlkider1286 19 дней назад

    Thanks ❤

  • @jessblair2834
    @jessblair2834 4 года назад +7

    hey friend, love your work always and forever but please check your solution to the first question. Should be local max.

  • @muhammadbilawal5403
    @muhammadbilawal5403 4 месяца назад

    thank you

  • @samerghanem599
    @samerghanem599 Год назад +2

    Hi, can anyone please post a link on how to factor multivariable functions as the one used in the video in form of binomials e.g. (x-y)(x+1)(x-1)

  • @byeol2412
    @byeol2412 3 года назад

    Thank you sir

  • @AZ-pn4sy
    @AZ-pn4sy 6 месяцев назад

    the first math should be local maximum ,thnx,great video,huge fan,just doing my work,so that others can follow through

  • @juanduarte200
    @juanduarte200 4 года назад +47

    On the second example, why do we chose (0,0) , (1,1) and (-1,-1) as our points of interest?

    • @abdelrahmanmahmoud5481
      @abdelrahmanmahmoud5481 4 года назад +1

      These points satisfy the two equation

    • @sadhiyausama9504
      @sadhiyausama9504 4 года назад +5

      If that is so, we can have points like (8,2) , (27,3).... also right? Do we need to consider points like these?

    • @trollguyawsomeness
      @trollguyawsomeness 4 года назад +28

      @@sadhiyausama9504 Those points aren't valid, as the
      fx value for f(8,2) would be 8(8^3-2)= 8(510) =/= 0
      Only the fy value would be 0, 8(2^3-8) = 8(8-8) = 0
      Only points that make both the derivatives 0 work
      The reason why f(-1,-1) works is because
      fx = 8(-1^3-(-1))= 8(-1+1) = 0
      fy = 8(-1^3-(-1))= 8(-1+1) = 0

    • @sadhiyausama9504
      @sadhiyausama9504 4 года назад +2

      @@trollguyawsomeness oh yeah!! Correct..I didn't think about fx..Thank you so much

    • @Sai1ence
      @Sai1ence 3 года назад +81

      The method isn't shown, but you just solve for a variable in the 1st equation and substitute for it in the 2nd so you only have an equation with respect to a single variable. Like this:
      First, our initial equations are:
      [1] 8(x^3 - y) = 0, [2] 8(y^3 - x) = 0
      We can divide equation [1] and [2] by '8' on both sides, as they equal 0. This will simplify stuff.
      [1] x^3 - y = 0, [2] y^3 - x = 0
      Let's try solving [1] for y:
      -> x^3 - y = 0 x^3 = y
      Well that was easy, wasn't it? Now we substitute for 'y' in equation [2] with the new value.
      [2] (x^3)^3 - x = 0 x^9 - x = 0 < [Factor] > x(x^8 - 1) = 0
      Now to solve this, we have 2 solutions:
      (1) x = 0, (2) x^8 - 1 = 0
      Since the exponent on 'x' in (2) is even, both x = 1 and x = -1 are solutions.
      Now finally to get their respective 'y', just plug it back into our original substitution.
      (1) x = 0, y = 0^3 = 0
      (2) x = 1, y = 1^3 = 1 OR x = -1, y = (-1)^3 = -1
      So our points of interest become: (0, 0), (1, 1), (-1, -1), as they are the only ones which satisfy both equations. They are the only possible critical points for the function. To figure out whether they are relative/local extrema, or simply saddle points, we use the double derivative test!

  • @mamatalama5713
    @mamatalama5713 3 года назад +1

    can you please make video for Cal3 Final review too????? Thank you!!!!

  • @totallytechalicious
    @totallytechalicious 8 месяцев назад

    Bless your soul

  • @tinashelazarus8737
    @tinashelazarus8737 2 года назад

    He's the best

  • @nancy-jx4nw
    @nancy-jx4nw 4 месяца назад

    You're amazing

  • @brysontownsend6305
    @brysontownsend6305 4 года назад +2

    You are a god. I appreciate all that you do

  • @mastersnoop454
    @mastersnoop454 3 года назад

    Tackar som fan my friend

  • @rafiyamajeed1102
    @rafiyamajeed1102 3 года назад

    Thanks

  • @markstar6899
    @markstar6899 Год назад +1

    is it possible for the local min or max be equal to zero, if so, whats the conclusion?

  • @bloxxastro1437
    @bloxxastro1437 2 года назад

    thx a lot

  • @abiademogboyinola2585
    @abiademogboyinola2585 3 месяца назад +1

    Pls how do you get the numbers you plug in as 2 for the first question?

  • @akashsamanta421
    @akashsamanta421 2 года назад

    Thanks ❤🌹🙏

  • @Rajivrocks-Ltd.
    @Rajivrocks-Ltd. Год назад

    In my Calc book it says the hessian (D in this case) = B^2 - AC but here I see it calculated as AC - B^2

  • @viditbhardwaj8726
    @viditbhardwaj8726 2 месяца назад

    Thaks

  • @ameer4142
    @ameer4142 3 года назад +1

    Pleased i need the playlist of this video

  • @tshinangakeith5819
    @tshinangakeith5819 3 года назад

    D > 0 and Fxx < 0 => Local Max

  • @evwerenisaacoghenenyerhovw232
    @evwerenisaacoghenenyerhovw232 4 месяца назад

    Thank u very much sir... God bless you
    Sir i will need videos on differentiatial equation and partial differentiation from first principle of multivariable.. can u help please

  • @rooneyotieno8074
    @rooneyotieno8074 2 года назад

    How do you determine the points of intrest

  • @Forum-la
    @Forum-la 3 года назад

    love u bro

  • @duarte338
    @duarte338 2 года назад

    Absolute life savior, god damn

  • @_lilpopsmoke3144
    @_lilpopsmoke3144 3 месяца назад +1

    Local min & max for multivariable functions

  • @amratefmohamed240
    @amratefmohamed240 2 года назад +4

    6:07
    Why did we say this point is local min , and the rule says if the second derivative is negative , it will be local max ?
    +
    Thank's so much on your effort.❤❤

    • @zeitgeistsandmicrocosms
      @zeitgeistsandmicrocosms Год назад

      Caught that as well, I assume it was a blunder

    • @imaivie
      @imaivie Год назад

      yeah same, i changed my notes and then realized oh wait no... he is wrong

    • @knanzeynalov7133
      @knanzeynalov7133 Год назад

      @@zeitgeistsandmicrocosms blunder :DDDDDDDDDDd

  • @namehere630
    @namehere630 3 года назад

    thank youuuuuuuuuu

  • @msesxv5661
    @msesxv5661 9 месяцев назад

    My future is depend on you thanks a lot!!!

  • @frankoluga4019
    @frankoluga4019 3 года назад

    how do we calculate fxy please

  • @ethanwagner7588
    @ethanwagner7588 Год назад +3

    P(2,2) is local max not min, u contradicted yourself.

  • @zameermohamed608
    @zameermohamed608 Месяц назад

    How was the points of interests for the 2nd question found???

  • @rookiemvp2008
    @rookiemvp2008 2 года назад

    BRO YOUR COMING IN FUCKING CLUTCH FOR MY CALC III EXAMS

  • @iiSnely
    @iiSnely 3 года назад

    god bless you

  • @rem6581
    @rem6581 4 года назад

    i just want to see his earlier vids

  • @thecupcakeman3087
    @thecupcakeman3087 7 месяцев назад

    How can i implent this when i have 3 variables and not only two ?

  • @melikipkoech9139
    @melikipkoech9139 3 года назад +2

    I think you confused on the example - when D>0 and f(xx)

  • @khwababamkhuseli9681
    @khwababamkhuseli9681 8 месяцев назад +2

    You made a mistake fxx0 it's not local min but local max

  • @sam_exc
    @sam_exc 2 года назад

    what happens in f(x,y)=(e^x)cosy?