At 4/28/08 04:06 PM, CatherineElizabeth wrote:
x = 0.9~
10x = 9.9~
10x - x = 9.9~ - x
9x = 9
x = 1
Therefore, 1 = 0.9~.
True, but the proof is idiotic, because you're practically using the assumption that 0.9~ = 1 to get to your answer. The only way that a number and ten times that number could possibly have a difference of 9 is if that number equals 1 to begin with. Simple algebra.
Besides, no one cares that 0.999... equals 1. It's just one of those silly facts that math professors use to confuse students, and there's no practical use for it, nor is there any reason to prove it unless you're too much of a douchebag to realize that any number with multiple consecutive nines after the decimal point should be rounded up anyway.
By the way, I can do stupid shit with numbers, too:
a = x
a+a = a+x
2a = a+x
2a-2x = a+x-2x
2(a-x) = a+x-2x
2(a-x) = a-x
Therefore, 2 = 1
Okay, so that's completely wrong. But you get the point.