Descartes Rule of Signs Calculator
Determine the possible number of positive and negative real roots using Descartes' Rule of Signs.
Enter Polynomial
For x³ - 2x² - 5x + 6, enter: 1, -2, -5, 6
P(x) =
x^3 - 2x^2 - 5x + 6
P(-x) =
-x^3 - 2x^2 + 5x + 6
Results
Degree of polynomial
3
Positive Real Roots
2 sign changes in P(x)
Possible: 2 or 0 positive roots
Negative Real Roots
1 sign change in P(-x)
Possible: 1 negative root
Coefficients
+1-2-5+6
Descartes' Rule of Signs
The Rule
- • The number of positive real roots equals the number of sign changes in P(x), or less by an even number.
- • The number of negative real roots equals the number of sign changes in P(-x), or less by an even number.
Example
P(x) = x³ - 2x² - 5x + 6
Signs: + - - + (2 changes)
→ 2 or 0 positive roots