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RE: Sqrt problem - restated



Paul,
Your equation still looks funny because of the formatting... I presume 
you mean
 eq ñ + Sqrt[a-b]*Sqrt[a+b]/Sqrt[a^2-b^2]

One way to do it is to use the rule (I believe Bob Hanlon wrote this in
 his response to your first note)

subst ÿqrt[x_]*Sqrt[y_] -> Sqrt[x*y] Simplify[eq/.subst]

And you will get your answer of 2.  Of course, it is up to you to ensure
 that the x and y actually DO satisfy the qualifications that you give
 them (real, positive).  If there are complicated expressions under
the  square root, this might not be obvious.

Hope that helps.

RF

-----Original Message-----
From:	PAUL REISER [SMTP:REISER@HRTS.NRL.NAVY.MIL] To:
mathgroup@smc.vnet.net
Sent:	Monday, April 27, 1998 12:47 AM To:	mathgroup@smc.vnet.net
Subject:	[mg12164] Sqrt problem - restated


That square root problem was a mis-statement on my part, but thank you
to everyone who helped. The problem I am having is something like how
do I get "2" out of this:

    Sqrt[a - b] Sqrt[a + b]
1 + -----------------------
               2    2
         Sqrt[a  - b ]

I'm starting to understand why Mathematica doesn't deal with this
because of the multiple value of square root, but if I know everything
under the square roots are positive, can I reduce this to 2 somehow
without substitution? (substitution would be prohibitively tedious in
my case)

Thanks for any help

        Paul Reiser




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