I learned that 0,999... = 1. I believe it was in M381 that I learned to prove it. The proof is quite simple actually.
x = 0,999..., multiply both sides with 10
10x = 9,999..., now subtract x from 10x
9x = 9, and we have our result
x = 1.
What I like about mathematics is that it is timeless, i.e. we can still read math books of hundreds of years old and still learn things from them. That's not an advisable strategy hfor any other science than mathematics. Of course, new branches of mathematics appear, new discoveries are made, but they don't invalidate the truths of the past.
Today however I found someone who actually is challenging some of the established truths in mathematics, like for example that 0,999... = 1. I don't think that he is a crackpot, although I have no doubt that the mathematical establishment, professors who are 'safe' by all means, will call him like that.
The man is arrogant though, he calls the proof above, 'juvenile' for example.
Who is he, what are his ideas and how did he disproof that 1 = 0,999? The links below will help you abshereing these questions.
- The New Calculus - The first rigorous formulation of calculus in history.
- Proof that 0.999 not equal 1.pdf
1-2015 When did it all start ?
4 days ago