End Behavior

Definition

End behavior refers to the way the values of a function behave as the input approaches positive or negative infinity. Understanding end behavior is crucial for analyzing functions, especially when determining horizontal asymptotes and the overall shape of their graphs. It gives insight into the limits of a function at infinity, which can help predict how a function will behave in extreme cases.

5 Must Know Facts For Your Next Test

1. The end behavior of a function is primarily determined by its highest degree term when dealing with polynomial functions.
2. For even-degree polynomials, if the leading coefficient is positive, both ends of the graph will rise towards infinity; if negative, both ends will fall towards negative infinity.
3. For odd-degree polynomials, if the leading coefficient is positive, the left end will fall to negative infinity while the right end rises to positive infinity; if negative, it’s the opposite.
4. Rational functions can also display different end behaviors based on their degrees; specifically, comparing the degrees of the numerator and denominator helps determine horizontal asymptotes.
5. End behavior can be visualized using graphs, allowing for predictions about a function’s behavior at extreme values without needing to calculate specific values.

Review Questions

• How does understanding end behavior aid in predicting the graph of a polynomial function?
  • Understanding end behavior helps predict how a polynomial function will behave at extreme input values by focusing on its leading term. The leading term determines whether the graph rises or falls as inputs approach positive or negative infinity. This knowledge enables you to sketch an accurate graph of the polynomial without plotting individual points, simply by knowing how it behaves at its ends.
• Discuss how the end behavior of a rational function differs from that of polynomial functions and what factors contribute to this difference.
  • The end behavior of rational functions varies based on the degrees of their numerator and denominator. If the degree of the numerator is less than that of the denominator, the end behavior approaches zero as x approaches infinity. If they are equal, it approaches a constant determined by their leading coefficients. This contrasts with polynomial functions, where only the leading term influences end behavior, highlighting how structure affects limits and asymptotes in different types of functions.
• Evaluate how changes in leading coefficients affect the end behavior of polynomial functions and provide examples to illustrate your analysis.
  • Changes in leading coefficients directly impact whether the ends of a polynomial function rise or fall as x approaches infinity. For instance, consider f(x) = x^3 (leading coefficient is +1) versus g(x) = -x^3 (leading coefficient is -1). In f(x), both ends rise (positive infinity on the right), while in g(x), both ends fall (negative infinity on both sides). This illustrates how simply flipping the sign of the leading coefficient can change an entire function’s end behavior.

Related terms

Horizontal Asymptote:

A horizontal line that a graph approaches as the input values go to positive or negative infinity, indicating the limit of the function's value.

Limit at Infinity:

The value that a function approaches as the input either increases or decreases without bound.

Polynomial Functions:

Functions that can be expressed in the form of a polynomial equation, which have specific end behaviors depending on their degree and leading coefficient.