Negative Square Roots on Calculators

Date: 10/30/95 at 14:44:17
From: Anonymous
Date: Mon, 30 Oct 1995 15:07:48 ARG

Every time I try to calculate on my calculator the square root of 
a negative number (-4, for example) I find the message "Error".  Why?
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E-mail: graciela@trilnick.satlink.net
Buenos Aires - Argentina

Date: 10/31/95 at 17:6:35
From: Doctor Ken
Subject: Re: (no subject)

Hello!

Well, that's because the way most people think about it, if you square
any real number, you always get a positive number.  So if you're trying 
to find the square root of a number (the inverse of squaring the 
number), you have to start out with a positive number.  

You actually _can_ do square roots of negative numbers if you're 
prepared to deal with things called "complex numbers."  There you define 
a number i by the property that i^2 = -1.  Then the square root of -4 
would be 2i.  But most calculators aren't fancy enough to handle stuff 
like that.

-Doctor Ken,  The Geometry Forum