= Solution
With three distinct positive <roots of an equation>, the negative-leading <cubic polynomial> has the sign pattern
$$
+\quad N_*\quad-\quad N_{**}\quad+\quad N_{***}\quad-.
$$
Equivalently its <derivative> is negative at the first <root of an equation>, positive at the middle <root of an equation>, and negative at the final <root of an equation>. The <phase line> arrows therefore point toward the two outer <equilibrium points> and away from the middle one:
$$
\boxed{N_*\text{ stable},\qquad N_{**}\text{ unstable},\qquad N_{***}\text{ stable}.}
$$
The middle <equilibrium point> separates the two <basin of attraction> in the <bistability> <mathematical model parameter> interval.
Back to article page
