PhiMed said:
Maze1125 said:
PhiMed said:
Um, sure hope you're trollin' here, because if not... whew.
Trolling about what?
About your 0.99... being equal to 1. It is not. Your "proof" is ridiculous.
What?
I haven't actaully given a proof so far.
Here's one though:
An infinite decimal is defined to be:
lim(as n->infinity)sum(from k=1 to n) (a_k * 1/10^k)
where a_k is the kth digit of the decimal.
Therefore, 0.999... is defined to be:
lim(as n->infinity)sum(from k=1 to n) (9 * 1/10^k)
So all we need to do is show that that is equal to one.
Which is true iff for all e>0 there exists an N such that for all n>N |1 - sum(from k=1 to n) (9 * 1/10^k)| < e
Now sum(from k=1 to n) (9 * 1/10^k) is a finite sum, and so we can calculate that
|1 - sum(from k=1 to n) (9 * 1/10^k)| = |1/10^n|
So we need to show that for all e>0 there exists an N such that for all n>N |1/10^n| =1 then |1/10^n| e>0, then let N = 1/e and then |1/10^n| N
Hence the claim that, for all e>0 there exists an N such that for all n>N |1 - sum(from k=1 to n) (9 * 1/10^k)| < e, is true.
So, by the definition of a limit, lim(as n->infinity)sum(from k=1 to n) (9 * 1/10^k) = 1
Therefore, by the definition of infinite decimals, 0.999... = 1
QED
Your statement that decimals are as exact as their ratio counterparts is misguided. If a ratio has a terminal decimal equivalent, then they are equal. If not, then our repeating decimal representations are not equal to the original ratio. They are simply the best representation we have in decimal.
You are wrong.
0.333... is exactly equal to 1/3.
I can give a proof if you insist.
Here's a tip: If you have to define a real number, the value of which is already known, your logic is flawed.
No, the exact opposite is true.
If you try to make an argument without clear definitions of what you're talking about then logic is impossible.
So, the fact that you had to "define" 0.99... as "The decimal representation of 1/3, times 3,"
I never did that.
I never actually defined 0.999... at all before this post was made.
A lot of arguments only occur because people are using two different definitions of the same word without realising.
in order for your "proof" to work should give you a clue that any math professor in this country would laugh in your face and maybe kick you out of their class if you tried to make that assertion more than once. Here's another "definition of 0.99..." for you: 0.99 repeating is the greatest real number that is less than one.
Wow, the irony of those two statements following each other is incredible.
There
isn't a number that has the property of being the greatest number less than 1.
And I doubt a maths professor would kick you out of his class for that mistake, but he would certainly try and explain to you how the Real Numbers work.
Take a computer algebra class, and one of the first things they'll talk about is rounding and calculation error, and this is one of the calculations they'll talk about.
If you've had a computer teacher who's claimed that 0.999... = 1 is due to a rounding error, then that teacher was
wrong, and you should probably take your own advice and talk to a mathematics professor about it.
Math people hate it when you reduce ratios to decimal before the proof is concluded,
Yes, they do, because it's far less neat on the page, not because it's inaccurate.