Added: 2 years ago
From: Entertainmentwf
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  • I hope I can understand it. I suck at math :P

  • you should really make it clear that A union B =/= Comp(A) union Comp(B), the correct equation for De Morgan's Law is Comp(A union B) = Comp(A) intersection Comp(B). You have to negate the left side and in your video I think you got confused when you thought your underline for De Morgan's law was the bar indicating the complement

  • @Dinunzilicious yes you are correct.  My apologies.

  • Great vid thanks alot, do you know of any websites where I can further learn about sets for like test prep??

  • @mosow09 It highly depends on what type of set theory you are using. For general set theory (the elementary kind) I would recommend really starting with things such as wikipedia then looking at problems over google (papers are great resources to look up results :D). Set theory has a lot of very powerful results that affect all the formal sciences greatly. :) A good place to start is with any online book that covers elementary set theory.

  • Good Explanation, found it easy to understand

  • great vid!!!

  • Why is that none of your other videos focus on math?

  • @ambigera I plan to do many more. I just tend to go on tangents with my theoretical stuff and my game development stuff.

  • cant relli hea him

  • The "set subtraction" thing described here afaik is usually called "symmetric difference", and the operation usually denoted by A - B or A \ B is the "relative compliment" meaning

    lambda a, b: [x for x in a if not x in b]

    (looks like python is the only language that can do this whose characters aren't blocked by youtube ^^)

  • lol, pretty much. I just stuck with the general definitions for ease of complexity..

  • You freak me out with your left handed writing. Great and helpful tutoral. helps alot.

  • anytime :D. Ya I'm a minority LOL. It even freaks me out LOL.

  • anytime :). Ever have any questions feel free to ask :D!

  • Haha... multiple MSN chimes.

    Math makes my brain hurt, but this was significantly more enjoyable than any "math" class I've ever had.

    I got the rest of it, but I'm a little confused about how the answer for that set subtraction you did was empty set and not {2} but I probably missed something.

    Nice whiteboard crisis aversion.

    And another great vid. =D

  • the reason it is empty set is because, we are subtracting from set A. Set subtraction is bizarre like that. If A doesn't have it then you can't subtract it.

  • So if it was B / A the result would be {2}, wouldn't it?

    Thank you! :)

  • yes :).

  • When using sets in alegebra do you need both of the notations? Set builder notation and the Roster notation? Can just the roster notation just be used alone?

  • you can use either. Builder notation works well with definitions. Typically when working with sets alone roster is good but, either is wonderful.

  • For example. The x=51, so cant that be writen as x={51} or x={-5,-4,-3,-2,-1,0,1,2,3,4,..­...51}

    Cant any varible represent an element or some kind of set? After all its a viariable and it has to be something like an integer, rational, irational number, right?

  • Okay to answer your questions :)

    {51} != 51. One is a set containing 51, and the other is just an integer of 51.

    Yes a variable can be represented as some set of values. Typical use is considered an array of elements in a set where you can iterate over some a_i contained in S. Sets can contain anything you like from symbols to algebraic expressions to variables and even operators.

    For the question about the 1st one. You can express the solutions as a set.

  • Can I write the Varibale in this algebraic equation as a set or an element of a set?

    Problem: Jeanne has $17 in her piggy bank. How much money does she need to buy a game that costs $68?

    Solution: Let x represent the amount of money Jeanne needs. Then the following equation can represent this problem: 17 + x = 68 We can subtract 17 from both sides of the equation to find the value of x. 68 - 17 = x

    Answer: x = 51, so Jeanne needs $51 to buy the game.

  • yes, you can. Typically when something is mathematically defined it usually is a set (an ordered pair within a set).

    Set Theory is nice since it is typically the foundation of mathematical definitions. For instead if you had variables x and y. If you had a Cartesian plane, the plane is made out of ordered pairs (x,y) which are contained in some set {x,y}. Functions in general are something called a bijection from x onto y f:x->y.

  • So the undefined variable is one of the those elements in that set? For example in physics you have M=MC squared, that famous Einstien equation. I know they are constants but since they are letters they can be shown as either integers, counting numbers or whole numbers, ect.

  • M = MC squared are all reals. Those are not countable since reals are not countable. One could use a set to contain the variables though :) within a given precision one could assign them (computer programs do something like this). S = {M,C} then if you say were doing the computation you could just store M and C within this set to save you computations later on :). You can literally use a set to be a collection of any set of objects as long as they are countable unless you want infinite sets.

  • If you wanted to denote this as a set relation you could easily use a function (like how the formula is given in) unless you wanted to represent variables and results. I hope that answers your question :).

  • yes thanks. That answerd it. So reals are the entire set of irrational numbers and rational numbers? Physics and science use big numbers and put exponents on them to denote how big the numbers are. So something like planks constant would be a Real number?

  • yes. Thats the reals. It is an infinite set (so it cannot be counted).

    Anything that is burden to error will be a real number (anything you would measure is real numbers since there is no such thing as an exact measure in empirical sciences). :)

  • Define what you mean by an undefined variable is one of the elements in that set?

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