Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site watmath.UUCP
Path: utzoo!watmath!ljdickey
From: ljdickey@watmath.UUCP
Newsgroups: net.math
Subject: Re Using square roots in proofs
Message-ID: <5757@watmath.UUCP>
Date: Tue, 13-Sep-83 10:42:17 EDT
Article-I.D.: watmath.5757
Posted: Tue Sep 13 10:42:17 1983
Date-Received: Wed, 14-Sep-83 00:25:02 EDT
Sender: ljdickey@watmath.UUCP
Organization: U of Waterloo, Ontario
Lines: 18

It is wrong to say that both 1 and -1 are square roots of 1.
Only one of them is a square root of 1, even though they
both square to 1.  
     Any decent modern calculus book will give you a good
example or two of this.  For instance, the widely used
text by Thomas, "Calculus and Analytic Gemoetry", 4th edition,
published by Addison-Wesley, on page 16 points out that
 
      the absolute value of x equals the square root
      of x squared.
 
Notice that this relies on the idea that the square root
be non-negative.

-- 
  Lee Dickey, University of Waterloo.  (ljdickey@watmath.UUCP)
                      ...!allegra!watmath!ljdickey
                ...!ucbvax/decvax!watmath!ljdickey