[qimg]http://farm7.static.flickr.com/6008/5961689020_957e098143_b.jpg[/qimg]
You have a penchant for turning something simple into something needlessly complicated. You don't need to convert to another base to uncover a problem with this particular proof that only works when the left side of the equation is strictly kept in the exact format and the right side in the approximate format all throughout. Here it is once again:
In this type of progress, the members of the left side are not evaluated in the approximate format, which allows the flow to reach the last line where the contradiction emerges. But in the all-format flow, the trouble start already in line 4 where
9x = 9
If you let the left side go to the approximate format and execute 9*x with x previously defined as x = 0.999..., then
9*0.999... = 8.999...1
and therefore it cannot equal 9.
The choice of preferring 0.999... = 1, baring the limit, instead of invoking a contradiction is simply wrong. It can be shown why: A contradiction of this kind is almost always preceded by a contradiction in some assumption, in this case that the expression "0.999..." is a real number. Here is the problem:
All manipulation that enter the various proofs, including the one that involves Dedekind cut, ask sooner or later and through different expressions for 0.999... = p/q. In other words, they ask for 0.999... to be a rational number. But there is no solution to p/q = 0.999... and therefore 0.999... cannot be a rational number. If not, then the only option left to place it is that 0.999... is an irrational number. That's can't be true, coz 0.999... has periodic fractional part and that fact places it into Q -- the rational numbers.
So by one definition, the expression 0.999... is a rational number, but by the other it is not. This contradiction must be resolved. There is an ongoing effort to resolve the issue. (I already posted a quote addressing that.) The only equation that sets correctly 0.999... = 1 is the one which shows that 1 is the limit of 0.999...
Hey, do you feel like do some base converting here?
That's the place where "0.999..." is asked to become a rational number and therefore a real number. It refuses, but the math folks would go ahead anyway, coz the God of Number Crunching would get upset, and you don't want that to happen, coz He is defined mean. Yep.