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Re: Solve Polynomial

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In article <jfdjr1$smo$1@speranza.aioe.org>, Nasser M. Abbasi
<nma@12000.org> wrote:

> On 1/20/2012 10:43 PM, Thomas Dean wrote:
> > Maple 15 does not produce a solution to diff(eq,x)=0;  But, one exists.
> >
> > eqn := (2*x^2-5*x+2)/(5*x^2-7*x-6);
> > deq:=diff(eqn,x);
> > solve(deq=0,x);
> > # returns no solution
> 
> I think if you plot  deq as function of x you'll see why
> there is no solution. deq is positive for all x.

and, simplified, deq = 11/(5*x+3)^2, so we can see it is never zero.
However, it has a pole at x=-3/5, maybe that is what you want to find?

> 
> > eq2 := op(1, deq) = op(2, deq);
> > solve(eq2,x,AllSolutions);
> > returns two solutions as I expect.
> >
> > numer(eqn) is zero at x=2 and x=1/2
> > denom(eqn) is zero at x=2 and x=-3/5
> >
> > eqn is zero at x=1/2 and undefined at x=2 and x=-3/5.  I assume 0/0 is
> > undefined.
> >
> > limit(eqn,x=2) is 3/13.
> >
> > How can I use solve to do produce a solution for diff(eq,x)=0?
> >
> > Tom Dean
>

-- 
G. A. Edgar                              http://www.math.ohio-state.edu/~edgar/

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Thread

Solve Polynomial Thomas Dean <tomdean@speakeasy.net> - 2012-01-20 20:43 -0800
  Re: Solve Polynomial "Nasser M. Abbasi" <nma@12000.org> - 2012-01-20 23:52 -0600
    Re: Solve Polynomial "G. A. Edgar" <edgar@math.ohio-state.edu.invalid> - 2012-01-21 07:35 -0700
  Re: Solve Polynomial Thomas Dean <tomdean@speakeasy.net> - 2012-01-21 10:01 -0800
    Re: Solve Polynomial Thomas Dean <tomdean@speakeasy.net> - 2012-01-21 10:09 -0800
    Re: Solve Polynomial Peter Pein <petsie@dordos.net> - 2012-01-21 19:50 +0100
  Re: Solve Polynomial acer <maple@rogers.com> - 2012-01-21 10:04 -0800

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