Re: Re: Function to solve polynomial

*To*: mathgroup at smc.vnet.net*Subject*: [mg71330] Re: [mg71298] Re: Function to solve polynomial*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Wed, 15 Nov 2006 06:43:30 -0500 (EST)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <ej42av$r0u$1@smc.vnet.net> <200611141006.FAA06667@smc.vnet.net>*Reply-to*: murray at math.umass.edu

Did I miss something? What's wrong with the following? p[x_] = Expand[(x - 4)(x + 2)(x - 1)(x + 5)(x - 7)] -280 + 194*x + 125*x^2 - 35*x^3 - 5*x^4 + x^5 Solve[p[x] == 0, x] {{x -> -5}, {x -> -2}, {x -> 1}, {x -> 4}, {x -> 7}} All output was converted to InputForm. dimitris wrote: > a1b2c3d4 wrote: >> I am trying to write a function that will help me solve the polynomial f(x)=(x-4)(x+2)(x-1)(x+5)(x-7) (NSolve and Solve functions not preferred) >> >> I can only think of this function: >> solution := {Plot[{(x -4)(x + 2)(x - 1)(x + 5)(x - 7)}, {x, -10, 10}, AxesLabel -> TraditionalForm /@ {x, y}]} >> >> Does anyone have better knowledge than me in writing an automated program to solve this polynomial? Say For, While or Do Loop? >> >> Your help will be greatly appreciated. > > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305

**References**:**Re: Function to solve polynomial***From:*"dimitris" <dimmechan@yahoo.com>