Jon G. wrote:
> ...
> A better strategy is to use the areas above and below the tangent line when 
> f(x) crosses the x-axis.
> 
As mentionned: if all works as you planed, you only find roots where the
sign changes.
But ok, you could look at f'(x) to find the roots where f(x) has a root
of even multipicity.

> g(x) = f '(x) x + b  equation of tangent line
> 

Mh, the equation of tangent line at x0 is
g(x) = f '(x0)(x-x0) + f(x0)
isn't it?

-- 
Dr. Detlef M$(D??(Bller,
http://www.mathe-doktor.de  oder http://mathe-doktor.de