[net.math] Why -1 =/= 1

lvc@cbscd5.UUCP (09/14/83)

The error in my 'proof' of -1 = 1 has to do with a wierd property of 
complex numbers.  

Here is the 'proof' again.

		-1 = -1  =>
		-1/1 = 1/-1  =>
		sqrt(-1/1) = sqrt(1/-1)  => (?)
		sqrt(-1)/sqrt(1) = sqrt(1)/sqrt(-1) =>
		sqrt(-1)*sqrt(-1) = sqrt(1)*sqrt(1)  =>
		-1 = 1

The problem is that sqrt(1/-1) =/= sqrt(1)/sqrt(-1).
sqrt(1/-1) is i, and sqrt(1)/sqrt(-1) is -i.  1/i = -i, not i.
The first time I saw this in 10th grade I was pretty shocked.

It seems that a lot of computer science people are getting hung up over
the fact that I said sqrt().  There is no other convenient way to express
the mathematicians function of square root (whose domain extends to all
real numbers, and complex as well) on a terminal.  Sorry for the
confusion.

Anyone figure out the error in the calculus 'proof' that 2 = 1 yet ?

Larry Cipriani
cbosgd!cbscd5!lvc