Checking the sign of a Mathematical expression

*To*: mathgroup at smc.vnet.net*Subject*: [mg66397] Checking the sign of a Mathematical expression*From*: "Bharat Bhole" <bbhole at gmail.com>*Date*: Thu, 11 May 2006 02:16:02 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hello: Is there a way in Mathematica to check whether an algebraic expression is positive or negative, and a way to specify conditions on the variables in the expression? For example, is there a way to check whether x^2 is positive for any real x? I want to check this for a complicated expression...basically the sign of the second derivative of a function. Thank you very much for your help. I am sorry for posting this message again. I had not used the appropriate subject line and thought I should change it.