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MathGroup Archive 2004

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Re: Number of roots from Solve?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg48457] Re: Number of roots from Solve?
  • From: Bill Rowe <readnewsciv at earthlink.net>
  • Date: Mon, 31 May 2004 00:13:33 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

On 5/30/04 at 6:12 AM, akoz at mimuw.edu.pl (Andrzej Kozlowski) wrote:

>I think having inexact coefficients does not make any difference
>here since I am pretty sure Solve first applies Rationalize to
>everything. In fact I don&t think it would not make any sense to do
>otherwise, given that Solve uses only algebraic and not numerical
>techniques. Since the equations are non-polynomial I can see
>nothing at all strange about them having very different numbers of
>roots.

I don't understand your comments regarding Solve and Rationalize. Why does the fac Solve uses algebraic techniques imply the usage of Rationalize?

If I do

Solve[x^2+.1 x + .01 == 0,x]

I get

{x->-0.1,x->-0.1}

and if I do

Solve[Rationalize[x^2 + .1 x + .01 == 0], x]

I get

{x->-1/10}, x->-1/10}

Doesn't that argue against Solve first applying Rationalize?
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