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 2021-01-03, 08:12 #67 SarK0Y     Jan 2010 10101102 Posts Side effect of research == $\sqrt{2}$ is the rational number https://alg0z.blogspot.com/2021/01/square-root-of-2-is-rational-number.html?m=0
2021-01-03, 08:16   #68
retina
Undefined

"The unspeakable one"
Jun 2006
My evil lair

22·5·307 Posts

Quote:
 Originally Posted by SarK0Y Side effect of research == $\sqrt{2}$ is the rational number https://alg0z.blogspot.com/2021/01/square-root-of-2-is-rational-number.html?m=0
For once I am pleased that the linked target displays nothing without JS, because just the title makes it look like a crank worthy post.

Would you like to summarise what it says?

2021-01-03, 10:04   #69
Batalov

"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

941710 Posts

In a nutshell, he says:
Let's take a rational number p/q = 2/3.
"but definition of the odd/even has absolutely no sense for rational numbers," (direct quote)
so we cannot say that integer p=2 is an even number. it's neither even nor odd. It is 1.99999999999... End of proof.

Is that right, Evgeniy? 2 is not an even number? Would it make you feel better, if p/q = 1414/1000, "we cannot prove that integer 1414 is an even number"?

I attached his "proof".
Attached Files
 Square root of 2 is rational number.pdf (131.9 KB, 23 views)

2021-01-03, 23:16   #70
SarK0Y

Jan 2010

2×43 Posts

Quote:
 Originally Posted by Batalov In a nutshell, he says: Let's take a rational number p/q = 2/3. "but definition of the odd/even has absolutely no sense for rational numbers," (direct quote) so we cannot say that integer p=2 is an even number. it's neither even nor odd. It is 1.99999999999... End of proof. Is that right, Evgeniy? 2 is not an even number? Would it make you feel better, if p/q = 1414/1000, "we cannot prove that integer 1414 is an even number"? I attached his "proof".
Åctually, no :) 2 is 2, but when you deal with rationals you cannot treat them like natural numbers. for example..
$\frac{1}{9}\cdot9 \neq\frac{9}{9}\cdot1$
at 1st glance, looks strange, but...
$\frac{1}{9}\cdot9 \eq0.11111111111111..11\cdot9$

according to the very principle of limits, approximation of continuous function cannot reach its final point. Here we could recall
Achilles and the Tortoise

 2021-01-03, 23:37 #71 VBCurtis     "Curtis" Feb 2005 Riverside, CA 13·367 Posts No, 1/9 times 9 is 1, even in decimals. 0.9999-repeating is equal to 1- yet you claim it is not, and make fuzzy reference to a limit. If it's not equal to 1, how far away from 1 is it? Or, what number can you fit between it and 1?
2021-01-03, 23:59   #72
SarK0Y

Jan 2010

2×43 Posts

Quote:
 Originally Posted by VBCurtis No, 1/9 times 9 is 1, even in decimals. 0.9999-repeating is equal to 1- yet you claim it is not, and make fuzzy reference to a limit. If it's not equal to 1, how far away from 1 is it? Or, what number can you fit between it and 1?
0.9 < 0.99 < 0.999< .. < 0.999..99 it's continuous sequence/function. if you assume it can reach its final point 1 then you fall into bad situation like..
$\lim_{x \to 1}\frac{1}{1-x}\eq \frac{1}{0}$

2021-01-04, 00:10   #73
Batalov

"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

223118 Posts

Quote:
 Originally Posted by SarK0Y Åctually, no :) 2 is 2, but when you deal with rationals you cannot treat them like natural numbers. for example.. <>
Don't get distracted.

Observe: a p/q is a rational number, where p is an integer and q is an integer..
Done with rationals. Now all you have are integer numbers until the end of Euclid's proof.

Now, are you saying that it's not true that all integer numbers are either even or odd? Hint: they are!

2021-01-04, 00:38   #74
VBCurtis

"Curtis"
Feb 2005
Riverside, CA

13·367 Posts

Quote:
 Originally Posted by SarK0Y 0.9 < 0.99 < 0.999< .. < 0.999..99 it's continuous sequence/function. if you assume it can reach its final point 1 then you fall into bad situation like.. $\lim_{x \to 1}\frac{1}{1-x}\eq \frac{1}{0}$
Neither side of your limit example exists, so your congruence is nonsensical- and irrelevant to whether 0.9-repeating is equal to 1.

There is no sequence involved in the single number 0.9-repeating, either. I didn't ask about 0.9, nor 0.99. 0.9-repeating is neither of those numbers. Every member of your sequence is strictly less than 0.9-repeating, anyway.

You might figure out the flaws in your reasoning if you used words properly- how do you define "continuous sequence"?

 2021-01-04, 01:15 #75 Dr Sardonicus     Feb 2017 Nowhere 452210 Posts (1) OP seems to be confounding "fractions" (rational numbers) and "decimal fractions," i.e. fractions that can be expressed with a power-of-ten denominator. Not all rational numbers are decimal fractions. (2) OP also seems to think that invalidating a proof of A automatically proves ~A (not-A). It doesn't. (Here, A is "The square root of 2 is irrational.") OP, of course, did not invalidate the proof. What he actually did was (1). Expressing the statement that the (positive) square root of 2 is rational as an equation in positive integers p and q, (*) p2 = 2*q2 invites a Euclidean proof that the square root of 2 is not rational, because the equation is impossible. Euclid also proved a result now known as the Fundamental Theorem of Arithmetic, AKA unique factorization. The equation (*) violates the Fundamental Theorem, because the left side is divisible by 2 evenly many times, while the right side is divisible by 2 oddly many times.
2021-01-04, 03:59   #76
SarK0Y

Jan 2010

2·43 Posts

Quote:
 Originally Posted by Dr Sardonicus (1) OP seems to be confounding "fractions" (rational numbers) and "decimal fractions," i.e. fractions that can be expressed with a power-of-ten denominator. Not all rational numbers are decimal fractions.
don't confuse numerical system & numbers itself == any proper numerical system can express any number. Another moment is how efficient that expression could be.
Quote:
 Originally Posted by Dr Sardonicus (2) OP also seems to think that invalidating a proof of A automatically proves ~A (not-A). It doesn't. (Here, A is "The square root of 2 is irrational.")
no, the very point is, you must uniform objects before you do operations on them. that proof messes w/ two different types of objects. for instance, 1/3 is odd or even? or let $p,q \in \mathbb{N}\; \frac{p}{q}=\epsilon,\; p=\epsilon\cdot q$ everything looks fine out there, right? But we have the damn grave problem, even two ones...
$p=\epsilon\cdot q$ exists everywhere for any p & q. second form has two troubling cases == 1st one w/ q = 0 and 2nd one is that..
$\displaystyle \lim_{q \to \infty}\lim_{p \to \infty}\frac{p}{q}\eq????$

2021-01-04, 04:00   #77
SarK0Y

Jan 2010

2·43 Posts

Quote:
 Originally Posted by VBCurtis Neither side of your limit example exists, so your congruence is nonsensical- and irrelevant to whether 0.9-repeating is equal to 1. There is no sequence involved in the single number 0.9-repeating, either. I didn't ask about 0.9, nor 0.99. 0.9-repeating is neither of those numbers. Every member of your sequence is strictly less than 0.9-repeating, anyway. You might figure out the flaws in your reasoning if you used words properly- how do you define "continuous sequence"?
so $\ln(x)$ and $\frac{d\ln(x)}{x}$ do not exist, right?
Quote:
 Originally Posted by VBCurtis There is no sequence involved in the single number 0.9-repeating, either. I didn't ask about 0.9, nor 0.99. 0.9-repeating is neither of those numbers. Every member of your sequence is strictly less than 0.9-repeating, anyway. You might figure out the flaws in your reasoning if you used words properly- how do you define "continuous sequence"?
Oh, boy, really?
$\lim_{n \to \infty}\left(1-\frac{1}{10^{n}\right)\eq0.9999..99$

Last fiddled with by SarK0Y on 2021-01-04 at 04:10

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