Re: A question about algebraic numbers using Mathematica

*To*: mathgroup at smc.vnet.net*Subject*: [mg62799] Re: [mg62762] A question about algebraic numbers using Mathematica*From*: Daniel Lichtblau <danl at wolfram.com>*Date*: Mon, 5 Dec 2005 13:41:03 -0500 (EST)*References*: <200512050837.DAA08323@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Kent Holing wrote: > I want to find the inverse of 2 - r in Q[r] where r is a root of the equation > x^4 - 2c x^3 + (c^2 - 2a^2) x^2 + 2a^2 c x - a^2 c^2 = 0 for a, b and c integers. > > Can this be done for general a, b and c? (I know how to do it for specific given numerical values of a, b and c.) > > Kent Holing <<Algebra`PolynomialPowerMod` InputForm[PolynomialPowerMod[2 - x, -1, x, {x^4 - 2*c*x^3 + (c^2-2*a^2)*x^2 + 2*a^2*c*x - a^2*c^2, 0}]] Out[5]//InputForm= PolynomialPowerMod[2 - x, -1, x, {-(a^2*c^2) + 2*a^2*c*x + (-2*a^2 + c^2)*x^2 - 2*c*x^3 + x^4, 0}] Daniel Lichtblau Wolfram Research

**Follow-Ups**:**Re: Re: A question about algebraic numbers using Mathematica***From:*Daniel Lichtblau <danl@wolfram.com>

**References**:**A question about algebraic numbers using Mathematica***From:*Kent Holing <KHO@statoil.com>