Analyzing a function with its derivative | AP Calculus AB | Khan Academy

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  • čas přidán 27. 08. 2024
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    Taking the derivative of f(x)=x_-12x+2 and graphing the derivative, so we can tell when f is increasing or decreasing, and where is its relative extremum points. Created by Sal Khan.
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Komentáře • 65

  • @komoyodo
    @komoyodo Před 9 lety +92

    Many lives were saved with the help of this video

  • @tshifhiwa1674
    @tshifhiwa1674 Před 5 lety +25

    Oh man, someday when I get rich I will make a handsome donation to your channel cause you rock dude!!!!

  • @kuroneko1374
    @kuroneko1374 Před 7 lety +49

    math is so pretty, I wish it was nicer to me.

  • @Mugen_YG
    @Mugen_YG Před 5 lety +5

    Khan, saving kids doing calculus since 2013

  • @abdilhakimable
    @abdilhakimable Před 10 lety +48

    WHAT THE FUNCTION

  • @DittyDafku
    @DittyDafku Před 5 lety +3

    You can also plug in a lesser number such as f'(-3) if you wanna check the sign and then for f'(0) to check the sign and then a final f'(3) to check the sign and give you the graph without having to draw it. This logic works because remember if at f'(-2) is a zero we are checking for a sign change on both sides so if you do this method you are basically inputting values before and after (-2) to evaluate and you do the same for (2) of course.

  • @rithvikshindihatti1215
    @rithvikshindihatti1215 Před 7 lety +37

    5:31 >What the fu..nction would look like.XD

    • @marwanamr97
      @marwanamr97 Před 7 lety +5

      LOL i thought i was the only one.

  • @raecooker
    @raecooker Před 6 lety +3

    *Critical point - where the derivative is equal to zero or does not exist/has a slope that equals zero.
    -How to find: Find the derivative of the function and set equal to zero
    -Each critical point can be labeled as a maximum or minimum
    >Maximum point - critical point in which the derivative goes from positive to negative
    >Minimum point - critical point in which the derivative goes from negative to positive
    *If the left side of the point is going up, it is approaching positive infinity, therefore the derivative is positive
    * If the right side of the point is going down, it is approaching negative infinity, therefore the derivative is negative

  • @Awgez24
    @Awgez24 Před 9 lety +20

    Graphing the derivative is sort of confusing. My teacher just taught us to make a chart and then just find where the derivative is positive and negative, making a local max/min. Just another method for someone who wants to try that.

    • @dr.mystic4789
      @dr.mystic4789 Před 7 lety

      after making the chart how did you find out the local max/min point

    • @flyin5952
      @flyin5952 Před 5 lety +5

      Magnesia _V i plugged in values to the right and left of each x root, then depending on whether that y outcomes were positive or negative, I could see if the graph had a change and therefore see if there was a local max / min (for ex.: if your root x was 0... if y outcomes to the left of 0 were negative, and y outcomes to the right of 0 were positive, that means there was a switch from negative to positive and therefore a local min. I’m sorry if that explanation wasn’t the best I’m just a student hope that helped tho!

  • @TheNinjabob1
    @TheNinjabob1 Před 9 lety +16

    You do know if you want an easier way to find maximum and minimum point, you can just differentiate it twice

    • @kanirudh123
      @kanirudh123 Před 4 lety +2

      That's just a working procedure!! You Need to understand the motive behind that!!

    • @levi2732
      @levi2732 Před 2 lety

      yeah but now you understand why we derivative the derivative !

  • @ian.ambrose
    @ian.ambrose Před 3 lety

    The way you emphasized "What the f.." startled me. 5:31

  •  Před 11 lety +1

    x^2 is parabolic which have minimum at [0,0], when you substract 12, whole function goes down by twelf.

  • @personc4638
    @personc4638 Před 9 lety +3

    SAL I LOVE YOU FOR EXPLAINING THIS. MY FRUSTRATION AND SUFFERING HAS FINALLY ENDED.

  • @insultobot
    @insultobot Před 11 lety

    I wish this was around when I was in high school. Thanks for continuing my education!

  • @Pankaj_prasad100
    @Pankaj_prasad100 Před 8 lety

    ur explanation is too good....u make people visualise..every thing thanx man.....

  • @S2DEliptiK
    @S2DEliptiK Před 8 lety +1

    Between -2 and 2 how do you decide which is a maximum and when it is a minimum? Negative values are always maximum values and positive values are always negative values?

  • @mujiburrahman4738
    @mujiburrahman4738 Před 3 lety

    Nice explanation
    Love from India

  • @fatima_nadeem
    @fatima_nadeem Před 3 lety

    This is such a great explanation. I wish my math teacher was like you.

  • @blueberry11051
    @blueberry11051 Před 11 lety +2

    Your voice sounda like music...no rather than a symhony..thanks a lot

  • @ThemisTheotokatos
    @ThemisTheotokatos Před 11 lety

    Sal, In the Greek Open Univercity EAP, we also do the so called infumum and supremum of function sequences. Make some videos about that to when you can.

  • @AniruddhaManu
    @AniruddhaManu Před 3 lety

    I have a question. As you've mentioned for a function to have a max / min value (i.e. for a function to have a critical point), f`(x) should be 0 and the value of x, thus obtained, +2 and -2 are considered as maximum / mimimum. This is where I am confused. Why have we considered that point as max/min value of the function? How do we confirm this, that it is a critical point not an inflexion point. I mean even inflexion point have f`(x) = 0 but there are no maximum / minimum value.

  • @mayur9876
    @mayur9876 Před 11 lety +2

    May be you can try hard examples. We want some insane problems. PLS

  • @Gabriel-qu5fb
    @Gabriel-qu5fb Před 6 lety +2

    this guy is so cute the way he repeats the words is too cute

  • @riyaazshaik369
    @riyaazshaik369 Před 7 lety

    For finding Max and Min, you checked the slope changing from positive to negative. Why did you go right to left? if we check from left to right, f(2) becomes max.

    • @TheKingmalik007
      @TheKingmalik007 Před 6 lety

      you count the numbers from -infinity to +infinity and that's what is represented in the number line. hence he moved from -ve to +ve as per the numbers represented on x-axis.

  • @bellajaid
    @bellajaid Před 6 lety

    Love your videos! Such a great supplement for my classes.

  • @PrashantSakoreGoLive
    @PrashantSakoreGoLive Před 9 lety

    Excellent job. Thank you so much!

  • @Sam-qf3sc
    @Sam-qf3sc Před 5 lety

    Thanks a lot

  • @kristyleung3149
    @kristyleung3149 Před 9 lety

    life saving videos indeed

  • @Lauderdalesfinest954754
    @Lauderdalesfinest954754 Před 11 lety

    Another Great Video..!

  • @millions2nette
    @millions2nette Před 7 lety

    I have a similar problem to this one in my Stewart 8th ed text, its num 4.1 ex 50. F(x) = x^3-6x^3+5...[-3,5]...I'm stuck on the part where you find the derivative and set to zero. No problem, but the solutions manual has a different answer for that. Unlike what you did which was take the square of 4 and come up with critical points (+ or - 2)...This manual factors out like this...3x(x-4) and ends up with the critical points (0,4). Please clarify this. Thank you

  • @kazbenzema
    @kazbenzema Před 10 lety

    good job Sal

  • @kirbycalitis345
    @kirbycalitis345 Před 6 lety +4

    I'm at 4th year level civil engineering and I dont rven understand any of these. What the function am I doing???

    • @abdib5446
      @abdib5446 Před 5 lety

      Kirby Calitis how the did you get it at the first place lol

    • @wolframalpha8634
      @wolframalpha8634 Před 5 lety

      @@abdib5446 😂😂😂😂😂

  • @alphabeyta
    @alphabeyta Před 10 lety +1

    5:31 WHAT THE FUNCTION?

  • @blinkanddie3397
    @blinkanddie3397 Před 11 lety

    BRILLIANT KHAN

  • @michaelsherwood1746
    @michaelsherwood1746 Před 5 lety

    this guy has saved me too many times to count

  • @Daan87423
    @Daan87423 Před 7 lety

    thanks

  • @shilosinjari4474
    @shilosinjari4474 Před 9 lety

    what if we have an absolute value function?

  • @Kdrama_narezka
    @Kdrama_narezka Před rokem

    how to solve y=3x^2-6x-1 this?

  • @gulsherbaloch4511
    @gulsherbaloch4511 Před 7 lety

    learn dear from these vedoes

  • @lordguthix1
    @lordguthix1 Před 11 lety

    Ur my live savior.... I needed help badly

  • @omgayo
    @omgayo Před 11 lety

    why f'(x) is draw like this ?

  • @informativecontent4778

    didn't undersatnd how u ound out the val was max

  • @SuperAbc2015
    @SuperAbc2015 Před 7 lety

    Why the screen be green

  • @nicholehall303
    @nicholehall303 Před 7 lety

    how is it that f'(-2)=3(-2²)-12 equal to 0.... don't know how u arrived at that zero cuz am getting -24

    • @satisfiction
      @satisfiction Před 6 lety

      The difference between "negative two, squared" (+4) and "negative, two squared" (-4) ;)

  • @user-ty2ob9yh9n
    @user-ty2ob9yh9n Před 8 lety +2

    why graphs of f'(x) looks like this?

  • @noobmaster-dm7tu
    @noobmaster-dm7tu Před 7 lety

    If the derivative curve [y= f' (x) ] has a negative slope at/ beyond a point, it means that the actual curve [y= f (x) ] has a positive slope corresponding to that point/ beyond it and vice versa.
    Correct me if I am wrong! :D

  • @saqibanjummasoodi
    @saqibanjummasoodi Před 3 lety

    5:31
    😂😂

  • @angelrosado3224
    @angelrosado3224 Před 9 lety +7

    Im too stupid to understand

  • @sudiptamittra2352
    @sudiptamittra2352 Před 2 lety

    🥰🥰

  • @kaylamoore144
    @kaylamoore144 Před 6 lety +1

    the only f(x) I want to care about is the girl group

  • @ib3scope
    @ib3scope Před 11 lety

    Woot! First Comment!! Go Sal!