Exact real solutions of cubic equations

*To*: mathgroup at smc.vnet.net*Subject*: [mg46932] Exact real solutions of cubic equations*From*: JonasB at iui.se*Date*: Tue, 16 Mar 2004 19:54:57 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Hello, I would like to find the _exact_ real roots of some cubic polynomials. Mathematica seems to have problems determining that a root is real Solve[1 + a s + b s^2 + s^3 == 0, s] results in three complex solutions for a = -4 and b = 3. FullSimplify does not help, either it does nothing or it gets stuck, depending on the values of a and b. I can of course evaluate the solution numerically, but that is not what I want. Does anyone know of a package that can simplify expressions with complex numbers? Jonas

**Follow-Ups**:**Re: Exact real solutions of cubic equations***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>