Top 4 Algebraic Tricks for Computing Limits

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  • Опубликовано: 6 окт 2024
  • We look at four common algebraic tricks used to compute limits, and see four examples of them. In all cases, these tricks help to take a limit which is in an indeterminant form (ex 0/0) and convert it into a determinant form that you can compute.
    Factoring: Separating out the same factor from the top and bottom means you can cancel it
    Expanding: Sometimes you need to multiply out and expression before you can see the canceling
    Common Denominator: When you have a sum or difference of fractions, you can combine the fractions into a single one with a common denominator
    Radical Conjugate: When you have expressions with square roots, often the radical conjugate is the trick you need
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    Now it's your turn:
    1) Summarize the big idea of this video in your own words
    2) Write down anything you are unsure about to think about later
    3) What questions for the future do you have? Where are we going with this content?
    4) Can you come up with your own sample test problem on this material? Solve it!
    Learning mathematics is best done by actually DOING mathematics. A video like this can only ever be a starting point. I might show you the basic ideas, definitions, formulas, and examples, but to truly master math means that you have to spend time - a lot of time! - sitting down and trying problems yourself, asking questions, and thinking about mathematics. So before you go on to the next video, pause and go THINK.
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Комментарии • 57

  • @JDean-oe1ux
    @JDean-oe1ux 13 дней назад +2

    I need a channel that explains "how" and "why" you do certain computations. They all pretty much say, "this is what you do, this is what you get." It assumes you know certain things that you don't. Thank you for the time and effort you put into this. I just need a channel for someone who is seeing this subject for the very first time.

  • @astradrian
    @astradrian 3 года назад +40

    I absolutely love your passion! Thanks for doing what you do!

  • @Three_Ducks_In_A_Trenchcoat
    @Three_Ducks_In_A_Trenchcoat Год назад +5

    Perfect summary before my first Calc test! Clarified what I had already figured out myself Perfectly!! Thank you so much!
    The comment on form was very helpful too!

  • @estellatrask5098
    @estellatrask5098 8 месяцев назад +3

    This was so helpful! Sometimes it’s nice for me to have the basics clarified!

  • @HarshitMahyavanshi-x5o
    @HarshitMahyavanshi-x5o 7 месяцев назад +2

    Even it's been 5 year the video is still amazing

  • @Anne25-g7d
    @Anne25-g7d 3 года назад +4

    Whoa! ! Algebraic key to unlock calculus. Factoring, expanding, common denominator, radical conjugate four computing nifty techniques.
    Thanking you sir! !

    • @DrTrefor
      @DrTrefor  3 года назад +2

      You're most welcom!

    • @mariamhammatto5753
      @mariamhammatto5753 День назад

      The same person who comments in every video i watch ❤

  • @novapearls
    @novapearls 2 года назад +6

    For the last one, x-4 = (sqr x-2)(sqrx+2)

  • @fatimasalem1021
    @fatimasalem1021 Месяц назад

    I’m literally crying, this vid helped me so much! Thnx to you Dr. Trefor!

  • @lonc57
    @lonc57 10 месяцев назад

    Thank you so much! You help me more than my own maths teacher!

  • @moderncitytv2818
    @moderncitytv2818 Год назад

    in fact you have really made my day great. God bless. i will be happy to get in touch with you sir

  • @SuperDeadparrot
    @SuperDeadparrot Год назад +2

    In the last one, could you not have recognized that the denominator is a difference of squares and if you factor it as such then terms cancel?

  • @GarryBurgess
    @GarryBurgess 2 года назад +1

    Clear! But I found your videos on LaTeX were a bit too fast for my brain. Maybe I just need to do the same thing on my computer. I still appreciate them.

  • @ryantexada9269
    @ryantexada9269 9 месяцев назад

    this video has taught me more in 7 minutes than my entire semester in calculus

  • @vijaysinghchauhan7079
    @vijaysinghchauhan7079 3 года назад +9

    When I factor, don't I change the domain or range of the function implicitly?

    • @DrTrefor
      @DrTrefor  3 года назад +21

      Indeed. But a limit doesn't care what happens AT the point, only around it.

    • @mariamhammatto5753
      @mariamhammatto5753 День назад

      ​@@DrTrefor👍🏻

  • @user-lp7tx1fe6t
    @user-lp7tx1fe6t 2 года назад +1

    Thank you for this

  • @BloobleBonker
    @BloobleBonker 2 года назад +1

    Very enjoyable thanks

  • @swaranvenkitesh7772
    @swaranvenkitesh7772 3 года назад +1

    Thank You Sir

  • @swaranvenkitesh7772
    @swaranvenkitesh7772 3 года назад +2

    Great Sir

  • @RamasyaDasosmyaham
    @RamasyaDasosmyaham 2 года назад +1

    Quick question: Why did you only use the positive root of 4 in the final evaluation step. If you used both roots - I.e. +/- 2 then you would get 2 solutions: 1/4 and +Inf, making the limit “DNE”?

    • @thomasfoster1985
      @thomasfoster1985 2 года назад +4

      sqrt(x) always means the non-negative root. If you want both you have to write ±sqrt(x).

    • @etienneduhoux
      @etienneduhoux 2 года назад

      Sqrt(4)=2. There is no others solutions

    • @squashedoranges7949
      @squashedoranges7949 Год назад +1

      I imagine it is assumed that the function is only defined for the reals.

  • @tanwarsingh396
    @tanwarsingh396 Год назад +1

    Nice sir 😊

  • @erromaissaeelhilali5121
    @erromaissaeelhilali5121 3 года назад +1

    Nice guys 😊👍👍👍

  • @MathCuriousity
    @MathCuriousity Год назад

    Why are we allowed to for example do x^2 divided by top and bottom since 0^2 is 0 and we would be dividing the top and bottom by 0. Isn’t that illegal?

    • @abhirupkundu2778
      @abhirupkundu2778 5 месяцев назад

      What you are dividing with is not exactly 0. We are seeing where the function's value approaches when plugging a number just close to 0, like 0.0000000000000000000000000000000000000000000000001 or -0.0000000000000000000000000000000000000000000000000001, see how close it is? Its squared is even smaller, like 0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001, but still not equal to 0. So you can divide by x^2 without breaking any math rules.

  • @saurabhsingh-ow7ue
    @saurabhsingh-ow7ue 4 года назад

    thank you sir..........

  • @navaryo_DIY
    @navaryo_DIY 9 месяцев назад

    I always use *L‘Hospital Theory* if the result is 0/0

  • @shishirupreti481
    @shishirupreti481 11 месяцев назад

    how do the terms cancel in numerator of no 4
    plzz help

  • @swaranvenkitesh7772
    @swaranvenkitesh7772 3 года назад +1

    Waiting For Many Video's

  • @bharathmurugan6675
    @bharathmurugan6675 3 года назад

    What if I get trigonometric functions ????

  • @luk4x126
    @luk4x126 2 года назад

    Bastion main???

  • @sq3614
    @sq3614 4 года назад +1

    Bonne vidéo

  • @Uday_003
    @Uday_003 Год назад

    dierectly we can use l hospital rule

  • @sergekamga4512
    @sergekamga4512 Год назад

    nice.!!!1

  • @awilmohamoud2721
    @awilmohamoud2721 2 года назад

    Allah is the Light of the heavens and the earth. The parable of His Light is as a niche and within it a lamp: the lamp is in a glass, the glass as it were a star Durriyyun, lit from a blessed tree, an olive, neither of the east nor of the west, whose oil would almost glow forth, though no fire touched it.
    The exact translation of the saying is, “I bear witness that there is no deity but Allah, and I bear witness that Muhammad is the messenger of Allah.”

  • @sauravuppoor2409
    @sauravuppoor2409 6 лет назад +1

    L'Hopital!

  • @ManzarMehmood-o8w
    @ManzarMehmood-o8w 6 дней назад

    I must say nice if i understud it😂

  • @solielriego9307
    @solielriego9307 3 года назад +1

    STEM PA

  • @chaitanyanile1185
    @chaitanyanile1185 7 месяцев назад +1

    Dont use lopitals rule because u r using limits to solve limits its a scam if you think on it 😂😂. If you dont care about scam then use it freely with all rules known about how to use it😅

    • @abhirupkundu2778
      @abhirupkundu2778 5 месяцев назад +1

      you can use L'Hopital's rule only during 0/0 or infinity/infinity forms cuz the 0/0 is actually not exactly 0/0, the numerator and denominator maybe just greater than 0 or smaller than 0.

  • @lianxiaotong
    @lianxiaotong Год назад

    Why this video has korean substitles

  • @null3007
    @null3007 Год назад

    w rizz

  • @davidmurphy563
    @davidmurphy563 2 года назад

    Ugh, I was following fine and now I have to look up what factorisation is.

    • @triple_gem_shining
      @triple_gem_shining Месяц назад

      Or what algebra is. How could you possibly get to calculus and not know that 😮

    • @davidmurphy563
      @davidmurphy563 Месяц назад

      @@triple_gem_shining When you're self taught, you inevitably miss things. I know factorisation now, needed it for eigenvectors.

  • @guyincognito7211
    @guyincognito7211 Год назад

    More efficient to find the LCD in part 3.