Limits by factoring | Limits and continuity | AP Calculus AB | Khan Academy

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  • čas přidán 21. 01. 2013
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    Sal finds the limit of (x_+x-6)/(x-2) at x=2 by factoring and simplifying the expression.
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Komentáře • 25

  • @mstsindia
    @mstsindia Před 11 lety +5

    He's using SmoothDraw with a Wacom tablet

  • @adjbutler
    @adjbutler Před 9 lety +18

    When he said the product of the two numbers had to equal -6 and the sum of the two numbers had to equal +3, he made a mistake. The sum had to equal 1 and the product had to equal -6.

    • @noelsukhai4754
      @noelsukhai4754 Před 3 lety

      Had me confused there too

    • @MatthewBendyna
      @MatthewBendyna Před 2 lety

      How do you arrive at that conclusion. In factoring, you usually want to account for all values of x, so (x+3)(x-2) doesn't seem to be a good factorization of x^2+x-6. If you try to simplify that through FOIL then you arrive at x^2-2x+3x-6, not the same answer. What formula is used to derive the rule "a number whose sum is 1 and whose product is -3".

    • @Poorly_Drawn_Science
      @Poorly_Drawn_Science Před měsícem

      thanks this was confusing me

  • @shiratori88
    @shiratori88 Před 11 lety

    Good luck may speed be with you on your future endeavor.

  • @totoblox4242
    @totoblox4242 Před 8 měsíci +2

    2:01 what happened to that voice change?😂

  • @Kvzjx2
    @Kvzjx2 Před 8 lety +1

    how did you know the y value for x =/ 2 was

  • @josephstein153
    @josephstein153 Před 6 lety

    When graduated high school in 1998 things where taught a lot different for ex. foil(first inner outer last) from algebra 1 can not be found on you site. You talk about factoring going back 2 basic algebra 1, but you don't give a link to it for people like me who forgot a few things over a decade of having no need for it. Can you please give a link on your exercises sheet to the relevant information, if it not to much work. Thanks.

  • @kahalamathvidz
    @kahalamathvidz Před 11 lety +1

    Hey sal, i wonder, what program your using. Because im trying to make videos too.

  • @TehMaxLightning
    @TehMaxLightning Před 8 lety +2

    Why is it that we can simplify the original expression and sub the limit in? My point is that we get the new expression from the original expression by simplifying it, as such the two expressions should be identical. However, substituting 2 for x gives undefined in the original expression and gives 5 in the new expression. How does that make sense? Shouldn't we get the same result?

    • @thepicmaster1385
      @thepicmaster1385 Před 3 lety

      plz tell me you figured this out by now im dying to know lol

    • @TehMaxLightning
      @TehMaxLightning Před 3 lety

      @@thepicmaster1385 hahaha sorry no idea, I never came back to it. I pass the torch on to you.

    • @thepicmaster1385
      @thepicmaster1385 Před 3 lety

      @@TehMaxLightning oh god im failing hahahah

  • @kahalamathvidz
    @kahalamathvidz Před 11 lety

    thnx man, but how to record it?

  • @gend6
    @gend6 Před 6 lety

    can someone help me how to get this on-screen calculator?

  • @wonderman8537
    @wonderman8537 Před rokem

    How did he know the y intercept is 3?

  • @shiratori88
    @shiratori88 Před 11 lety +1

    My First first Comment :)

  • @matif118
    @matif118 Před 11 lety

    why don't u use the de l'Hospital?

  • @Aylou07
    @Aylou07 Před 4 lety

    Jajajajjaja vine buscando nivel y contre el nivel más difícil

  • @kewlkrew100
    @kewlkrew100 Před 11 lety

    You should really do Let's Plays of Minecraft. You have the perfect voice for it and you are smart, which is good for Minecraft.

  • @jackuy12345
    @jackuy12345 Před 11 lety

    sal how come I cant find these videos in playlist? Can you add them in your calc playlist?

  • @lahiru1k
    @lahiru1k Před 5 měsíci

    aughhhhhhhhhhhhhhhhhhhhhhhh

  • @shiratori88
    @shiratori88 Před 11 lety

    Sorry Bro you were about a 1 minute too late :(