technique used in algebra to determine the number of positive and negative real roots of a polynomial equation. The rule provides a way to estimate the number of real roots based on the number of sign changes in the polynomial's coefficients when arranged in descending order of their powers.

Here's a summary of Descartes' Rule of Signs:

Positive Real Roots: To estimate the number of positive real roots of a polynomial, write down the polynomial in standard form with terms arranged in descending powers. Count the number of sign changes in the sequence of coefficients. The actual number of positive real roots of the polynomial is either equal to the number of sign changes or less than that number by an even integer.