At 4/29/08 04:20 PM, Mind-Edge wrote:
At 4/28/08 09:48 PM, Glaiel-Gamer wrote:
lim(x -> infinity) 1 - 1/x
This just means it's approaching 1, but never reaching it.
Ok try this then
lim (x -> 4) x = 4
By your logic, that means that x is approaching 4 but never reaching it. Ya, that's what the limit means, however because you don't get a /0 effect at x = 4, then the limit to and the value of x at 4 are the same thing.
You don't get a 1/0 error in 1 - 1/x when x is infinity, therefore the limit of and the value at are exactly the same.
It reaches it at infinity. In order to deal with infinity in math, you cannot treat it as a concept, but must instead treat it as a number with its own special properties.
x can be any real number other than infinity (or 0) in this case
x/inf = 0
inf + x = inf
inf / x = inf
inf / inf = undefined
inf * x = inf
inf * inf = inf
inf / 0 = undefined
inf * 0 = 0
These definitions are standard and used in all upper level math courses (like calculus)
At 4/29/08 04:20 PM, Fyndir wrote:
At 4/29/08 04:19 PM, Glaiel-Gamer wrote:
You didn't prove that 24.9 = 1, you proved that 24.9/24.9 = 1
He didn't prove that 0.9 = 1, he proved that 0.9/0.9 = 1.
What's your point again?
Look at his other 2 equations there.
Equation A was the definition of a repeating decimal series (for .999....)
Equation B was how to solve for an infinite series.
Plug equation A into equation B and you get his part C, which evaluated the infinite series as .9/.9, or 1.
Seriously, the only people that dispute the FACT that 1 = .999.... are people who have not reached or taken upper level math classes.