use local linear approximation, no calculator!

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  • čas přidán 4. 04. 2022
  • Approximating cbrt(1001) by using calculus, no calculators!
    Check out how to use Newton's Method to approximate an irrational number: • approximate 4th root o...
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Komentáře • 43

  • @DeJay7
    @DeJay7 Před 2 lety +44

    "Approximate cbrt(1001) up to 2 decimal digits"
    Sure: 10.00

  • @dimitris17
    @dimitris17 Před 2 lety +49

    I'm an engineer and answer is π^2

    • @hata6290
      @hata6290 Před 2 lety

      WHAT

    • @two697
      @two697 Před 2 lety

      You mean pi^2

    • @navra3173
      @navra3173 Před 2 lety +11

      @@hata6290 pi squared is equal to 9.8 ≈10 ( which is also equal to acceleration due to gravity of earth )
      Conclusion, g ≈ pi^2 ≈ 10

    • @dimitris17
      @dimitris17 Před 2 lety +5

      @@navra3173 you mean that g=π²=e²

    • @midnightgamer4201
      @midnightgamer4201 Před 2 lety

      No 10(g) is not equal to 9(pi^2) is not equal to 4(e^2)

  • @rahenson1
    @rahenson1 Před 2 lety +10

    Once you have the formula seems it would have been easier to leave the 1/300 outside than distribute. Plug in 1001 for x and you just have 10 + (1/300) * 1 or 10 and 1/300.

  • @MsBombastik
    @MsBombastik Před 2 lety +4

    End made my smile. Instead of just ignoring x-1000 we go through half as many steps as entire calculation.

  • @hata6290
    @hata6290 Před 2 lety

    I LOVE THIS GIY

  • @goblinthebuble
    @goblinthebuble Před 5 měsíci

    Thank you

  • @yamikira6512
    @yamikira6512 Před 2 lety +15

    Make a function f(x)=x^3-1001 and use Newton's Method

    • @bprpcalculusbasics
      @bprpcalculusbasics  Před 2 lety +1

      😆

    • @givrally7634
      @givrally7634 Před 2 lety +1

      Well, you do get 10+1/300, which is the same answer linearization gets you.
      Wait no actually this makes sense since Newton's method is basically just linearization but in reverse. Instead of saying "I know this function's value at a nearby point and I want to approximate the value at my point of interest" you say "I want to find what my point of interest is, and I know a point that's very close to it". Instead of knowing the y values and working with that, you know the x values and you work with that. So yeah it makes sense after all.

    • @vizart2045
      @vizart2045 Před rokem

      Easier to differentiate

  • @AnakinSkywalker-zq6lm
    @AnakinSkywalker-zq6lm Před 2 lety +10

    3 take it or leave it

  • @itsphoenixingtime
    @itsphoenixingtime Před 2 lety +6

    Binomial expand (1+x)^n with n as 1/3, x = 0.001, then multiply the result by 10. since cbrt1001 = cbrt1000 * cbrt 1.001 = 10 cbrt 1.001
    lets try it!
    (1+x)^n = 1 + nx + n(n-1)/2 x^2 + ..... (since x = 0.001 it will be very small, we can just use up to the 2nd power
    1 + 1/3 (0.001) + (1/3)(1/3 - 1)/2 (0.001)^2 + .......
    1 + 1/3000 - 1/9000000
    = 1 + 2999/9000000
    Multiply by 10
    = 10 + 2999/900000
    Approximated value: 10.0033322222....
    Actual value of cbrt 1001 = 10.0033322228
    Very close!

  • @aasthaiitbombae5750
    @aasthaiitbombae5750 Před 2 lety +1

    Got to learn something new :)

  • @Can-hb6ls
    @Can-hb6ls Před 2 měsíci

    thx lord

  • @chitlitlah
    @chitlitlah Před 2 lety +10

    The result on the left is still hard to convert to decimal without a calculator. It seems like a wasted effort to me. The one on the right is reasonable if you somehow find yourself without a calculator and need a closer estimate than just 10.

    • @ieatgarbage8771
      @ieatgarbage8771 Před 2 lety +5

      No one’s actually doing this because they need it lol
      but if you want
      1001/300+20/3
      3001/300
      10+1/300
      10.00333…

    • @rubenverg
      @rubenverg Před 2 lety +3

      you can just ignore the last steps, back when you have 10 + (x-1000)/300 just plug in x = 1001 and get 10 + 1/300, which is quite obviously 10.00(3)

  • @zayedalsuwaidi7697
    @zayedalsuwaidi7697 Před měsícem

    2:33 when you rewrote x to the power of -2/3 isn’t it supposed to be the cube root of the square of 1000?

  • @matteocilla9482
    @matteocilla9482 Před 2 lety

    taylor development 🤪i love it

  • @fanigamotoqueiro502
    @fanigamotoqueiro502 Před 2 lety +3

    10

  • @SJrad
    @SJrad Před 2 lety

    Minisculely greater than 10

  • @sahilmengji5687
    @sahilmengji5687 Před 2 lety +1

    Better use binomial approximation

  • @arcturusgd
    @arcturusgd Před 2 měsíci

    The differential form is easier to me

  • @NoNameAtAll2
    @NoNameAtAll2 Před 2 lety

    wait, did RedpenBlackpen change name?

    • @NoNameAtAll2
      @NoNameAtAll2 Před 2 lety

      oh, it just doesn't have bprp listed in Channels section...

  • @moeberry8226
    @moeberry8226 Před 2 lety

    This was not needed this is already so close to 10 at 2 decimal places.

  • @norman4628
    @norman4628 Před 2 lety +2

    Or just use a calculator

    • @jase4066
      @jase4066 Před 2 měsíci

      No it's no fun 😊

  • @tubax926
    @tubax926 Před 2 lety +2

    Just use a calculator bro it's 10.00333

  • @williamhewitt4748
    @williamhewitt4748 Před 2 lety +2

    10