Derivatives of inverse functions | Advanced derivatives | AP Calculus AB | Khan Academy

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  • Опубліковано 9 лют 2025
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    Functions f and g are inverses if f(g(x))=x=g(f(x)). For every pair of such functions, the derivatives f' and g' have a special relationship. Learn about this relationship and see how it applies to __ and ln(x) (which are inverse functions!).
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КОМЕНТАРІ • 50

  • @xox0babe
    @xox0babe 5 років тому +288

    i love how i have a derivative test tomorrow and inverse functions STILL confuse me

    • @xox0babe
      @xox0babe 5 років тому +27

      update: four days after my calc test and i figured it out yay !

    • @demahalfaiz9946
      @demahalfaiz9946 5 років тому +7

      @@xox0babe love that for u :')

    • @wesleylai2895
      @wesleylai2895 4 роки тому +2

      this is me RIGHT NOW

    • @xox0babe
      @xox0babe 4 роки тому +1

      @@wesleylai2895 good luck!!

    • @starwarfan8342
      @starwarfan8342 4 роки тому +1

      @@xox0babe What you get on the test tho?

  • @priyanshulal7790
    @priyanshulal7790 Рік тому +18

    Last minute review at 3 am before my midterm 😭

  • @victorserras
    @victorserras 6 років тому +37

    There is a much better way to think of the derivative of the inverse function: don't put the derivative of the inverse in the denominator. That is the derivative you want to find out, so why would anyone put it in a denominator?
    You get this:
    g'(f(x)) = 1/f'(x).
    But then you have to remember that f(x) is just equal to y. So f(x) = y. Then you can just simplify as g'(y) = 1/f'(x).

    • @antoniovianaaa
      @antoniovianaaa 4 роки тому +1

      Great coment. Thank you, mate!

    • @alzero4621
      @alzero4621 4 роки тому +5

      Agreed that we are looking for g' and not f'. IMO the best way to find g' based on knowledge of f' is the following: f(g(x)) = x --> f'(g(x))*g'(x) = 1 --> g'(x) = 1 / f'(g(x)). Example: d ln(x) / dx = 1 / e^(ln(x)) = 1 / x, where e^(ln(x)) is the derivative of e^x at ln(x). To be fair, Sal kind of hints at this at the end, but should be explained explicitly in lieu of the other direction that he did explain.

    • @cariboux2
      @cariboux2 Рік тому

      Thank you!!!

  • @_sunny__moon_
    @_sunny__moon_ 4 роки тому +9

    stan khan academy guy for clear skin

  • @oxydol3456
    @oxydol3456 Рік тому +2

    Impress with the clean and easiness of this trick. really easier than calculating about limit to get derivatives .

  • @legendj.a291
    @legendj.a291 Рік тому +6

    Pov: you are studying Calc. and forgot about algebra & pre.

  • @rashedulislam2645
    @rashedulislam2645 4 роки тому +1

    Thank you from Bangladesh.....

  • @user-gt6fn2tu3k
    @user-gt6fn2tu3k 3 роки тому +7

    You know its a quality content if its Khan Academy😃💙

  • @gbvortex_0077
    @gbvortex_0077 8 місяців тому

    Complexity persists if finding inverse of a function is tough

  • @hongyunxu6018
    @hongyunxu6018 4 роки тому +4

    damn,I spent an hour on my textbook trying to understand this concept and I couldn't get it. And your video just helped me understand it in 2 minutes lol. Thank you!

  • @fet1612
    @fet1612 3 роки тому +2

    2:16
    The derivative of a function and the derivative of its inverse are related

    • @jonathanhughman154
      @jonathanhughman154 6 місяців тому

      Yes, original function is rise/run and its inverse is run/rise. So just take reciprocal of derivative of corresponding point

  • @cassied9327
    @cassied9327 4 роки тому

    Great video!

  • @chrisfreilich
    @chrisfreilich 2 роки тому +7

    I'm still stuck on the chain rule concept, shown again here. We've learned previously that the notation d/dx [g(x)] is the same as g'(x). So here, we see that d/dx [g(f(x)] is actually g'(f(x))*f'(x). So, d/dx (g(x) should simultaneously be g'(f(x)) AND g'(f(x))*f'(x). I get that somehow the phrase 'with respect to...' plays a part here, but in this video, there's no indication that g'(f(x)) is 'with respect to' anything in particular. If someone could help me with this, I feel like it's all downhill from here!

  • @charlielazoQ
    @charlielazoQ Рік тому

    Great video but it really confused me when they found the derivative of f(x) instead of g(x) which is the inverse of f(x), but it's basically the same thing anyways.

  • @SameerSk
    @SameerSk 7 років тому +4

    Make a lot of videos on permutations and combinations

  • @AlexPiotrowski
    @AlexPiotrowski 7 років тому +2

    3rd! lol the comments on khan academy is much better than the youtube comments

  • @maggieburns8155
    @maggieburns8155 2 роки тому

    what program does he use to do this?

  • @giannapedroza1986
    @giannapedroza1986 4 роки тому +5

    When you unironically say "the number E"

  • @ms97
    @ms97 6 років тому +1

    nice

    • @ms97
      @ms97 6 років тому

      neat

  • @ImInayat
    @ImInayat 7 років тому +1

    please make a video on Lean Six Sigma

  • @h0tie
    @h0tie 7 років тому +1

    I trust in Khan Academy 🎊☑

  • @s.denizkaradag6619
    @s.denizkaradag6619 4 роки тому

    g(f(x)) isn't equal to 1 cuz we can write it as g(x) o g-1(x) and isn't this equal to 1 am i remember wrong?

  • @SameerSk
    @SameerSk 7 років тому +1

    Make videos on circular permutations

  • @SeriesKJ
    @SeriesKJ 7 років тому +1

    By any chance is there a video discussing Constant Of Proportionality? I need it.....

    • @yordanazzolin
      @yordanazzolin 7 років тому +1

      SeriesKJ i don't think there's enough to say about it to make a video honestly; there's just one thing x proportional to y mean x= c * y and c is your constant or proportionality if you know x and y it's basic algebra to find c (spoiler x/y = c)

  • @amritkumar844
    @amritkumar844 5 років тому

    Wow

  • @romanfernandez4055
    @romanfernandez4055 2 роки тому

    ur going too fast

  • @jingy205
    @jingy205 3 роки тому

    the inverse of e^x is actually just e^x..

  • @cristhianlucas2301
    @cristhianlucas2301 7 років тому

    será traduzido para português ?

    • @jonschwann
      @jonschwann 6 років тому

      Cristhian Lucas no hasta ahora

    • @maxwellsequation4887
      @maxwellsequation4887 2 роки тому

      Translation
      Ronaldo Ronaldo RONALDOOOOOO
      GOOLLL GOL GOL GOL GOOAAALLL!!!!

  • @xDementedPhantom
    @xDementedPhantom 7 років тому +1

    Yo

  • @veemeow123
    @veemeow123 7 років тому +1

    !!!!

  • @spamsingles5948
    @spamsingles5948 7 років тому +3

    1st