Re: help with polynomial solutions

*To*: mathgroup at smc.vnet.net*Subject*: [mg81781] Re: help with polynomial solutions*From*: "David Park" <djmpark at comcast.net>*Date*: Wed, 3 Oct 2007 02:36:39 -0400 (EDT)*References*: <fdt3dv$rqj$1@smc.vnet.net>

You could use CoefficientList first and then Solve. a x^2 + b x + c == x^2 First[%] - Last[%] == 0 MapAt[CoefficientList[#, x] &, %, 1] // Thread Sort@First@Solve[%, {a, b, c}] -- David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ "Jules P. Aronson" <aronson at nlm.nih.gov> wrote in message news:fdt3dv$rqj$1 at smc.vnet.net... >I could not get mathematica to solve the following class of problems. > > If f(x) and g(x) and two polynomials then a solution to force f(x) to be > equal to g(x) is the equate the coefficients of f(x) to be the same as > those of g(x). For example, > > a x^2 + b x + c == x^2, has a solution, a=1, b=0, c=0. > > If I do the following in mathematica: > > Solve[a x^2 + b x + c == x^2, {a,b,c}] or using Reduce, I do not get the > desired solution. > > Can someone tell how to force mathematica to solve such problems. >