Descartes' rule of signs - Polynomial Functions

Descartes' rule of signs

Lessons

Notes:
Descartes' Rule of Signs For a polynomial P(x)P(x):
\bullet the number of positive roots = the number of sign changes in P(x)P(x), or less than the sign changes by a multiple of 2.
\bullet the number of negative roots = the number of sign changes in P(x)P(-x), or less than the sign changes by a multiple of 2.

Note: Before applying the Descartes' Rule of Signs, make sure to arrange the terms of the polynomial in descending order of exponents.

trick of Descates' rule of signs
  • Intro Lesson
    Introduction to Descartes' Rule of Signs
  • 1.
    Use Descartes' Rule of Signs to Determine the Number of Positive and Negative Roots
    Use Descartes' Rule of Signs to determine the possible number of positive roots and negative roots:
  • 2.
    Use the Rational Roots Theorem, together with Descartes' Rule of Signs, to Find Roots Effectively
    Solve:
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Descartes' rule of signs

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