Definite integral as the limit of a Riemann sum | AP Calculus AB | Khan Academy

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  • เผยแพร่เมื่อ 1 ม.ค. 2025

ความคิดเห็น • 82

  • @goldminer1815
    @goldminer1815 7 หลายเดือนก่อน +10

    Was confused about the difference between Riemann sum calculations and integral calculations for a bit, this vid cleared it right up. When we do Riemann sum problems, we use a small, finite amount of rectangles represented by n, calculate their areas, then add their areas together to find an approximated area under the curve, we know that the true area is somewhere between the area of the left endpoint and the area of the right endpoint. Whereas with an integral, we essentially eliminate the error completely by using Riemann sum to calculate the area under the curve as n (number of rectangles) goes to infinity, leading to a more accurate result.

  • @hennywisetheclown
    @hennywisetheclown 11 ปีที่แล้ว +131

    Is he using a mouse or a pen to write this? because if he's using a computer mouse, he's a fucking boss

    • @vasukumar5727
      @vasukumar5727 3 ปีที่แล้ว +14

      he probably be using a pen.

    • @henloworld514
      @henloworld514 3 ปีที่แล้ว

      @@vasukumar5727 ye

  • @SebastianLopez-nh1rr
    @SebastianLopez-nh1rr 9 ปีที่แล้ว +18

    I just gained a deeper understanding of calculus in 4 minutes

  • @mattt2684
    @mattt2684 6 ปีที่แล้ว +25

    Absolutely GREAT explanation!

  • @vasukumar5727
    @vasukumar5727 3 ปีที่แล้ว +4

    i can binge watch his videos for whole day.

  • @ryanolstad1540
    @ryanolstad1540 10 ปีที่แล้ว +38

    He sounds like Paul from Llamas with Hats

  • @SSJayMariano
    @SSJayMariano 10 ปีที่แล้ว +70

    Replay 3:10 for Sal the Seal XD

  • @adrianaquispepoma665
    @adrianaquispepoma665 7 ปีที่แล้ว +6

    thank you so much! Good video hope you can make more videos about the Riemann sum and
    integral

  • @longhorn4500
    @longhorn4500 12 ปีที่แล้ว +3

    The word 'lim' here means that you cannot tell the difference between real area and the integral. The difference between real area and definite integral might be 0 and might be > 0. But in the second case you still cannot give the number that is less than the definite integral. So, it is not just 'a good approximation'. It is the best.

    • @dnuma5852
      @dnuma5852 ปีที่แล้ว

      its not the best approximation either because its not an approximatiob

  • @GenghisVern
    @GenghisVern 12 ปีที่แล้ว +18

    The guy made great noodle soup too!

  • @tiancichen5769
    @tiancichen5769 5 ปีที่แล้ว +1

    he's everywhere when i open youtube for edu. eco and maths. he is the big boss coooool~~~

  • @JH-ux1re
    @JH-ux1re 2 ปีที่แล้ว +2

    Much better than my textbook. I don’t understand why they use so many words to explain math. Only by the several lines on this screen I understood it better than reading my textbook and taking my calculus 1 class

  • @nick60444
    @nick60444 11 ปีที่แล้ว +6

    Supposed to create a loop in matlab that does this...so that's why I'm looking at this video

  • @BL0XXOR
    @BL0XXOR 8 ปีที่แล้ว +10

    So Billy, how do you find the area of a square? RIEMANN SUMS!!!

  • @mohenderthakur1642
    @mohenderthakur1642 7 ปีที่แล้ว +1

    woh that's very good for understanding

  • @drallisimo34
    @drallisimo34 9 ปีที่แล้ว +2

    great explanation!!!

  • @AbhishekSingh-pp1ks
    @AbhishekSingh-pp1ks 4 ปีที่แล้ว +1

    3:11

  • @vagelis454
    @vagelis454 5 ปีที่แล้ว

    beautiful video.Love u guys!

  • @ianbaladiang9320
    @ianbaladiang9320 3 ปีที่แล้ว

    Thank you 💗

  • @minimeowmania
    @minimeowmania 12 ปีที่แล้ว +3

    This would have helped hours ago before I took a test on this

  • @vighneshramesh2569
    @vighneshramesh2569 9 ปีที่แล้ว +14

    just use 1.5 speed and listen, it is much much better

  • @Bbne420
    @Bbne420 6 ปีที่แล้ว +5

    *infinitely small*

  • @saurabhsingh-ow7ue
    @saurabhsingh-ow7ue 4 ปีที่แล้ว

    thank you sir...

  • @HenggaoCai
    @HenggaoCai 12 ปีที่แล้ว +1

    you have to take the limit as x approaches infinite of the sum to get rid of the spaces between the rectangles

  • @victorwhite8356
    @victorwhite8356 7 ปีที่แล้ว

    when can we just eliminate the sigma sign when taking the derivative of an infinite sum. I mean, for example we have the sum from 1 to infinity of 1/n; and that is equal to the integral from 1 to infinity of 1/n (which is lnn) plus the Euler-Mascheroni constant. In that case I guess we can take its derivative by simply eliminating the sigma, so it will be the limit when n tends to infinity of 1/n. When can someone do that same thing with other infinite sums?

  • @LanRous
    @LanRous 12 ปีที่แล้ว

    A definite integral is the real value of the area of a positive function or just a good approximation?

    • @sarahkaveh7739
      @sarahkaveh7739 4 ปีที่แล้ว +1

      An infinietly good aproximation

  • @mtbva
    @mtbva 9 ปีที่แล้ว

    This guy's voice is beautiful

  • @batytom1
    @batytom1 8 ปีที่แล้ว +97

    This didn't help me at all...

    • @mirknankazmzad8517
      @mirknankazmzad8517 7 ปีที่แล้ว +5

      because he made like an intro, did not do any example

    • @worldsstrongestgamer4033
      @worldsstrongestgamer4033 ปีที่แล้ว

      Did you find the help you needed

    • @manarsalem1685
      @manarsalem1685 10 หลายเดือนก่อน +3

      I think you better start from the very beginning, he has a list on the website. It's best to follow the list order on the website. They have exercises as well for each lesson.

    • @worldsstrongestgamer4033
      @worldsstrongestgamer4033 10 หลายเดือนก่อน +3

      Yo guys I passed the course

  • @chuckmanacsa
    @chuckmanacsa 9 ปีที่แล้ว +1

    what is the difference between areas and reman sums?

    • @SebastianLopez-nh1rr
      @SebastianLopez-nh1rr 9 ปีที่แล้ว +1

      +Charles Manacsa none

    • @ss-sv4vj
      @ss-sv4vj 8 ปีที่แล้ว

      Charles Manacsa negligible

    • @DittyDafku
      @DittyDafku 6 ปีที่แล้ว +2

      I know this probably doesnt matter to you anymore but, for others. The Riemann sum is just the sum of all the parts, it does not have to mean total area. Why? Because if the graph has negative area, the Riemann sum would not give you an accurate number. Can the Riemann sum mean area? yes, but only if the function is positive all the way through, if it is not, then you have to calculate each individual part and add their absolute values to get area.

  • @lollel1490
    @lollel1490 3 ปีที่แล้ว +1

    I don’t get how riemanns sum has anything to do with the actual mathematical process of integration

  • @peelysl
    @peelysl 3 ปีที่แล้ว +2

    I'm an incoming 7th grader and I find this very fascinating. (:
    ps. I'm going into Alg2 and participate in AMC8

  • @Nikifuj908
    @Nikifuj908 12 ปีที่แล้ว +3

    That's true, I guess. But you still can't always use a definite integral. There are functions without antiderivatives.

  • @utkarshsinghal5
    @utkarshsinghal5 12 ปีที่แล้ว +6

    reimann : ramen

  • @longhorn4500
    @longhorn4500 12 ปีที่แล้ว

    But we can divide it into several continuous parts and integrate on them.

  • @Dan-gc3ke
    @Dan-gc3ke 6 ปีที่แล้ว +1

    why is delta x = (b-a)/n?. I get how b-a is delta x, why is it being divided by n?

    • @Gwyn94
      @Gwyn94 6 ปีที่แล้ว +2

      n is the number of rectangles. b-a gives you the overall delta x of the function over the interval [a,b], and dividing that by n number of rectangles gives you the delta x (or width) of each individual rectangle

  • @ibrahim9296
    @ibrahim9296 12 ปีที่แล้ว

    Will there be a proof of why the area is antiderivative?

  • @HenggaoCai
    @HenggaoCai 12 ปีที่แล้ว +1

    Rieman Sum is only an estimate of the area. For a more accurate value, you should always use a definite integral

    • @vasilymelnikov7346
      @vasilymelnikov7346 3 ปีที่แล้ว +1

      The limit of a Riemann sum is equal to the integral

  • @jitendragupta1239
    @jitendragupta1239 6 ปีที่แล้ว

    wt is diff betwn integral and riemann integral

  • @teemomain330
    @teemomain330 วันที่ผ่านมา

    Riemann is a sigma male 🤫🤔🗿

  • @hallmorales
    @hallmorales 11 ปีที่แล้ว

    German mathematician Bernhard Riemann

  • @saeta
    @saeta 8 ปีที่แล้ว +1

    Is the trapezoide rule a Riemman sum?

  • @hawkscout17
    @hawkscout17 12 ปีที่แล้ว

    don't you mean x approaches 0? n is supposed to go to infinity

  • @NH-zh8mp
    @NH-zh8mp 2 ปีที่แล้ว

    No it’s not, Bernhard Riemann didn’t define integral for continuous function, but for bounded function, which can not be done using limit. He used infimum and supermum to define the integral.

    • @Ayham-kg5sc
      @Ayham-kg5sc 9 หลายเดือนก่อน

      could you recommened any video to help understand that

  • @longhorn4500
    @longhorn4500 12 ปีที่แล้ว

    By the way, if you integrate sine from -pi/2 to pi/2, you get 0. You can make some interesting conclusions out of this.

    • @rohansingh1057
      @rohansingh1057 5 ปีที่แล้ว +3

      but what is interesting about that sin is an odd function and is supposed to show this behaviour

  • @Wheeintage
    @Wheeintage 3 ปีที่แล้ว

    I used to hate maths

  • @05ioio
    @05ioio 10 ปีที่แล้ว +1

    Good explanation but change background color

  • @wr0aig
    @wr0aig ปีที่แล้ว

    i'm going to eat beirneahrd riemann

  • @1o20h5
    @1o20h5 3 ปีที่แล้ว

    easy

  • @Nikifuj908
    @Nikifuj908 12 ปีที่แล้ว

    Except you can't always use a definite integral, especially if the function is discontinuous somewhere on the interval.

    • @vasilymelnikov7346
      @vasilymelnikov7346 3 ปีที่แล้ว

      You can though since the set of discontinuities has measure 0

  • @mryup6100
    @mryup6100 4 ปีที่แล้ว

    yes.no

  • @mrsadman13
    @mrsadman13 6 ปีที่แล้ว

    A

  • @cookiesrain
    @cookiesrain 10 ปีที่แล้ว

    Nice voice haha

  • @mrsadman13
    @mrsadman13 6 ปีที่แล้ว

    S