Even Functions

Definition

An even function is a function where the value of the function is the same for inputs that are equidistant from the origin, but on opposite sides. In other words, for any input x, the function value f(x) is equal to the function value f(-x).

5 Must Know Facts For Your Next Test

1. Even functions satisfy the equation f(x) = f(-x) for all x in the domain of the function.
2. The graph of an even function is symmetric about the y-axis, meaning the left and right halves of the graph are reflections of each other.
3. Polynomials with only even-powered terms, such as $x^2$, $x^4$, and $x^6$, are examples of even functions.
4. Trigonometric functions like $\cos(x)$ and $\cosh(x)$ are even functions, while $\sin(x)$ and $\tanh(x)$ are odd functions.
5. Identifying whether a function is even or odd can help simplify the analysis and understanding of the function's behavior.

Review Questions

• Explain the defining characteristic of an even function and how it relates to the function's graphical representation.
  • The defining characteristic of an even function is that the function value f(x) is equal to the function value f(-x) for all x in the domain of the function. This means that the graph of an even function is symmetric about the y-axis, where the left and right halves of the graph are reflections of each other. This symmetry property allows for the simplification of the analysis and understanding of the function's behavior, as the function values on one side of the graph can be determined from the values on the other side.
• Describe the relationship between even functions and odd functions, and provide examples of each type of function.
  • Even functions and odd functions are two distinct classes of functions that exhibit different symmetry properties. While even functions satisfy the equation f(x) = f(-x), odd functions satisfy the equation f(x) = -f(-x). This means that the graph of an odd function is symmetric about the origin, where the left and right halves of the graph are reflections of each other, but with opposite signs. Examples of even functions include $x^2$, $\cos(x)$, and $\cosh(x)$, while examples of odd functions include $x^3$, $\sin(x)$, and $\tanh(x)$. Understanding the distinction between even and odd functions is crucial for analyzing the properties and behavior of various mathematical functions.
• Explain how the identification of a function as even or odd can simplify the analysis and understanding of the function's behavior, and provide a specific example to illustrate this concept.
  • Identifying a function as even or odd can significantly simplify the analysis and understanding of the function's behavior. For example, if a function is known to be even, then its values on the negative side of the x-axis can be directly inferred from its values on the positive side, as the function values are the same. This allows for the reduction of the domain that needs to be considered when studying the function's properties, such as its range, critical points, and extrema. Similarly, for an odd function, the values on the negative side of the x-axis can be determined by taking the negative of the corresponding values on the positive side. This symmetry property can greatly simplify the analysis of the function's behavior and its applications in various mathematical contexts.

Related terms

Odd Functions:

An odd function is a function where the value of the function changes sign when the input is negated. In other words, for any input x, the function value f(x) is equal to the negative of the function value f(-x).

Symmetry:

Symmetry refers to the property of a function where certain transformations, such as reflections or rotations, leave the function unchanged.

Graphical Representation: The graphical representation of an even function is symmetric about the y-axis, meaning the graph is a mirror image on both sides of the y-axis.