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Mathematics 8 Online
OpenStudy (perl):

Q

OpenStudy (squirrels):

A

pooja195 (pooja195):

spam?

OpenStudy (mikeymaximum):

WUH!!!

OpenStudy (perl):

sorry typo

OpenStudy (perl):

mouse + keyboard fail

OpenStudy (sleepyjess):

:) we all make them

pooja195 (pooja195):

yep :D

OpenStudy (perl):

:)

OpenStudy (solomonzelman):

perl, lol! Is that going to be a tutorial about a set of all rational numbers or something?

OpenStudy (perl):

maybe i should :)

OpenStudy (solomonzelman):

... elaborate on the question:)

OpenStudy (perl):

help me define Q , the set of rational numbers

OpenStudy (perl):

what is an element of Q exactly

OpenStudy (solomonzelman):

Respectively, 1. natural numbers 2. whole numbers (adding 0 to #1) 3. integers (saying negative integers as well) 4. fractions (positive or negative) that don't have any non-perfect-square square roots, euler number and other irrationals in them. basically all reals besides irrational numbers. or do you want something involving crazy scearing notations?

OpenStudy (solomonzelman):

scaring*

OpenStudy (perl):

Hmmm, I want a well defined set Q , and you gave me duplicates "1/2 = 2/4 = 3/6 = ... "

OpenStudy (solomonzelman):

did I say that?

OpenStudy (perl):

you said fractions?

OpenStudy (solomonzelman):

\(\large\color{slate}{ 2.3/4.7 }\) is also a rational

OpenStudy (solomonzelman):

but, I am saying it is everything asides from irrationals. my best and shortest definition.

OpenStudy (solomonzelman):

http://mathworld.wolfram.com/RationalNumber.html

OpenStudy (solomonzelman):

for smarties. but I am not in that list of ppl

OpenStudy (perl):

agreed. You can also mention when two rational numbers are equal, that way your set Q is not full of duplicate numbers

OpenStudy (perl):

im kinda getting at equivalence classes, thats a better definition of Q

OpenStudy (solomonzelman):

Well, I also find that \(\large\color{slate}{ Q}\) stands for "quotients" and that is true, to be most "narrowed" rational number is fraction (saying it is certainly an integer, but to be most percise a fraction).

OpenStudy (perl):

when someone says they are thinking of the rational number 1/2, there are many ways to represent this rational number. but the number is unique itself

OpenStudy (perl):

I will say that a/b = c/d iff ad = bc .

OpenStudy (perl):

that way there is no ambiguity when you look at a fraction (using integers in numerator and denominator) , what rational number you are dealing with

OpenStudy (solomonzelman):

surely

OpenStudy (solomonzelman):

I like that abcd thingy:)

OpenStudy (perl):

Yes, you can construct rational numbers using integers, which is cool. From the other direction, if you start by assuming the existence of real numbers, you can define rational numbers in terms of repeating decimals or terminating decimals .

OpenStudy (solomonzelman):

oh, I left out repeat./term. decimals... btw, what is the latex for a repeating decimal?

OpenStudy (solomonzelman):

And yes, but you don't have to use integers. you can use decimals to construct rational numbers.

OpenStudy (solomonzelman):

I mean they will becomes integers as \(\large\color{slate}{ 1.2/2.3~~~~--->~~~~12/23}\)

OpenStudy (perl):

right

OpenStudy (solomonzelman):

(as some say) A set of all rational number is a combination of different rations of \(\large\color{slate}{ a/b}\) where \(\large\color{slate}{ a}\) and \(\large\color{slate}{ b}\) are integers.

OpenStudy (perl):

oh I meant if you start with R , the real numbers, you can define rational numbers as the subset of repeating or terminating decimals. For example .11111... = 1/9 .121212...= 4/33 , etc

OpenStudy (solomonzelman):

well, it is true though, as I said, decimal reduce to integers

OpenStudy (perl):

and I guess I defined R implicitly as infinite decimals :)

OpenStudy (perl):

sorry, i meant R = set of all infinite decimal

OpenStudy (perl):

you can define R in other ways as well

OpenStudy (solomonzelman):

Yes, R is not imaginary. lol jk

OpenStudy (perl):

:L

OpenStudy (solomonzelman):

wait that is not a laplace I hope

OpenStudy (solomonzelman):

:)

OpenStudy (perl):

i think theres a nice Latex font for R, C, Q

OpenStudy (solomonzelman):

maybe

OpenStudy (solomonzelman):

1. integers = discrete function 2. rational numbers = relations 3. real numbers = relations involving Euler numbers like \(\large\color{slate}{ \pi}\) and \(\large\color{slate}{ e}\) I haven't even been a fan of definitions.

OpenStudy (solomonzelman):

or for 3, squares roots too

OpenStudy (solomonzelman):

or other roots

OpenStudy (perl):

just a question on your comments

OpenStudy (perl):

you said decimals reduce to rational numbers 1.2 /2.3 what about .11111... / .121212...

OpenStudy (solomonzelman):

well, those infinite decimals are fractions, in actuallity, aren't they?

OpenStudy (squirrels):

I thought perl fanned me at first, but it turned out it was just a notification that he replied to this post haha:P looks like im going to put the champagne back in the cooler..

OpenStudy (perl):

right

OpenStudy (solomonzelman):

yeah:P

OpenStudy (perl):

just checking :) hi squirrel @Squirrels

OpenStudy (solomonzelman):

\(\large\color{slate}{ \sqrt{2} / \sqrt{8}}\) is rational.

OpenStudy (solomonzelman):

lol

OpenStudy (perl):

hmm :)

OpenStudy (squirrels):

Hey bud, good job with your work. Continue my friends.

OpenStudy (solomonzelman):

it is

OpenStudy (perl):

right

OpenStudy (perl):

1/2

OpenStudy (solomonzelman):

duh...:D

OpenStudy (perl):

so , looks can be deceiving (that is the moral here)

OpenStudy (solomonzelman):

Yes:) And that is how decimal/decimal is rational too

OpenStudy (solomonzelman):

" don't just take it as it is, play with it! "

OpenStudy (solomonzelman):

When we use a squeeze trm, btw..... for floor function x

OpenStudy (solomonzelman):

I lagged

OpenStudy (perl):

squeeze term for floor function , explain /elaborate

OpenStudy (solomonzelman):

\(\large\color{black}{ \displaystyle \frac{\lfloor x \rfloor }{x} }\)

OpenStudy (perl):

thats an interesting function

OpenStudy (perl):

the limit is 1 as x-> oo ?

OpenStudy (solomonzelman):

for instance, \(\large\color{black}{ \displaystyle\lim_{x \rightarrow ~{\Large \pm}\infty} \frac{\lfloor x \rfloor }{x} =1 }\) where \(\large\color{black}{ \displaystyle\lfloor x \rfloor }\) is a floor function of x. but will just take \(\large\color{black}{ \displaystyle\lim_{x \rightarrow ~{\Large }\infty} \frac{\lfloor x \rfloor }{x} =1 }\) for now,

OpenStudy (perl):

so you can break it down , first consider integer values, then non integer values?

OpenStudy (solomonzelman):

If you take: \(\large\color{black}{ \displaystyle \frac{x-1}{x}<\frac{\lfloor x \rfloor }{x} < \frac{x}{x} }\)

OpenStudy (perl):

ohh

OpenStudy (solomonzelman):

I am bringing this up in relation to rational numbers.

OpenStudy (perl):

there should be an equal sign somewhere there

OpenStudy (solomonzelman):

well,|dw:1422401089450:dw|Syou are right

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