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Re: How to get sqrt(Year^2)===Year?

• To: mathgroup at smc.vnet.net
• Subject: [mg75795] Re: [mg75724] How to get sqrt(Year^2)===Year?
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Thu, 10 May 2007 05:26:51 -0400 (EDT)
• Reply-to: hanlonr at cox.net

Sqrt[(-3)^2]

3

You have to indicate that the variable is (real and) nonnegative

Simplify[Year == (Year^2)^(1/2),Year>=0]

True


Bob Hanlon

---- Hatto von Aquitanien <abbot at AugiaDives.hre> wrote: 
> If I have some expression which takes the square root of a square, it
> evaluates leaving the whole square root expression unchanged.  
> 
> Year == (Year^2)^(1/2)
> 
> just returns what I entered when evaluated.
> 
> Year == Year
> 
> evaluates to True.
> 
> How do I persuade Mathematica to evaluate the first expression completely?
> -- 
> http://www.dailymotion.com/video/x1ek5w_wtc7-the-smoking-gun-of-911-updated
> http://911research.wtc7.net
> http://vehme.blogspot.com
> Virtus Tutissima Cassis
>