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/sci/ - Science & Math

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File: 44 KB, 2554x398, 999_Perspective[1].png [View same] [iqdb] [saucenao] [google]
3813909 No.3813909 [Reply] [Original]

i was trying to convince the dunces in my class that 0.9 recurring equals 1. no matter how many proofs i gave them, it was clear they didn't understand the concept of infinity so i thought i might as well do an appeal to authority and enlist the maths teacher's help...
>her: no, they're different
>me: different representations but equal right?
>her: only if you round 0.9 recurring
can any maths teacher really be that uninformed? i didn't have time to show her the proof because i had to go but shouldn't she know this already?

>> No.3813913

>>3813909
qualifications for said math teacher:

protip: when you say teacher, i'm thinking HS teacher.

>> No.3813915
File: 138 KB, 1290x1845, 0.9=1.png [View same] [iqdb] [saucenao] [google]
3813915

>>3813909

>> No.3813925
File: 43 KB, 350x494, archimedes.jpg [View same] [iqdb] [saucenao] [google]
3813925

1>0.9
1>0.99
1>0.999
...
1>0.99...9
No matter how many nines you take 1>0.99..9
Thus
0.999... != 1

>> No.3813929

>>3813913
16-19 year old college/sixth form, like halfway between high school and university. i don't know what the american equivalent is. but you're right, it's probably closer to hs than uni

>> No.3814018

>>3813929
6th form is the same as American HS

>> No.3814035

Mathematically does 1/3 = .333... or is it an approximation?

>> No.3814048

>>3813915

But when you're talking about infinite convergent sums, you're talking about the limit. So that proof is still a bit counterintuitive.

>> No.3814054

>>3814048

****er, though, I still agree that the proof is correct, I just saw a little irony in saying that 1 was the limit for that sum.

>> No.3814073

>>3813909
Jesus, op. I hope you're trolling. Fuck.

>> No.3814086
File: 113 KB, 953x613, maths.jpg [View same] [iqdb] [saucenao] [google]
3814086

>> No.3814138

Goddammit, I don't know what to believe anymore. I clearly do not understand this.

>> No.3814141

"If we have some expression involving a variable x, say, and we consider the limit of that expression as x approaches a fixed value a, then to say that “the limit exists” and is equal to some value L is not to say that the expression itself is ever equal to L, or even that x is ever equal to a. Indeed, what makes limits interesting and useful is that it very often happens that x can't be a, but can only become arbitrarily near to a."

It appears that 1 != .999..., or at least a proof using a limit is erroneous. Are there any proofs that don't use a limit in some way? I feel like they have to if it involves an infinite number of decimals.

From some random website:
http://www.mathacademy.com/pr/prime/articles/limits/index.asp

>> No.3814146

>>3814035
it's the same number yes

>> No.3814147

>>3814141

eh, decimation. You get my drift.

>> No.3814259

>>3813909
>can any maths teacher really be that uninformed?
Highschool, yeah, in fact most are.
College/University? No, they shouldn't even be able to get the job at that rate.

>>3813929
>halfway between high school and university. i don't know what the american equivalent is.
The equivalent to half way between highschool and university is staying at home unemployed and smoking weed.

>> No.3814411

no trolling in this thread?!

wtf happened to my /sci/, is summer finally over? :D