Simplify stuck in simple expression

*To*: mathgroup at smc.vnet.net*Subject*: [mg50127] Simplify stuck in simple expression*From*: carlos at colorado.edu (Carlos Felippa)*Date*: Mon, 16 Aug 2004 06:45:34 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hi - I wonder why Simplify[(2 - Sqrt[72*(1+a*b)^2+4])/(2*a)]; in v. 4.2 gets stuck. It does not reduce the expression to (1 - Sqrt[18*(1+a*b)^2+1])/a; FullSimplify and declaring-variable-attribute variations do not work. What is necessary for the simplification to happen?