Descartes's Rule of Signs
Descartes's rule of signs estimates the greatest number of positive and negative real roots of a polynomial .[more]
Delete any zeros in the list of coefficients and count the sign changes in the new list. If the number of changes is , then the maximum number of positive roots is one of , , ….
To get the maximum number of negative roots, use the same procedure for . The coefficients for and are shown in the second and third rows of the table.[less]