ebw on 30 April 2013
| dsgrue3 said: x = 2 x^2 = 4 x = +/- 2 Fuzzy math is fuzzy. This is why it doesn't sit well with me. I understand it through Pezus' example with fractions, but this isn't an equation. It's just an assertion. It isn't a proof at all. Surely you admit -2 != 2? |
You are deeply misguided about what a proof is. Your calculation begins with the premise that x=2 and deduces that x = ±2, which I completely agree with. You seem to misunderstand what the ± notation means. The last sentence reads "x must be either 2 or -2", which of course it is, since we happen to know it is 2. There is nothing in the sentence "x = ±2" that says that x could be -2, only that x cannot take any other value. Likewise, Pezus's example seeks to show that if x has any value whatsoever, it must be 1. Reading this as "-2 = 2" is utter nonsense.
