Polynomial Behavior and Theorems
Cubic functions (polynomials with degree 3) create S-shaped curves with interesting features. When graphing any polynomial, look for relative minimums (valleys where the function changes from decreasing to increasing) and relative maximums (peaks where the function changes from increasing to decreasing).
Two important theorems govern polynomial behavior. The Factor Theorem states that a polynomial f(x) has a factor xโk if and only if f(k)=0. This helps us find zeros of polynomials, which are the x-values that make the function equal zero.
The Fundamental Theorem of Algebra guarantees that a polynomial of degree n will have exactly n roots (though some may be complex or repeated). The behavior at these zeros depends on their multiplicity:
- Odd multiplicity: the function crosses through the x-axis
- Even multiplicity: the function touches the x-axis and bounces back
Remember This: The end behavior of a polynomial (how it acts as x approaches positive or negative infinity) depends on its degree and leading coefficient. Even-degree polynomials have matching end behaviors, while odd-degree polynomials have opposite end behaviors.
Understanding these patterns makes sketching polynomial graphs much easier - you can predict how the function will behave without plotting every point.