Skip to main content
Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Not the one you use?Change textbook
Chapter 7, Problem 7.AAE.17

17. Even-odd decompositions
b. If f(x) = f_E(x) + f_O(x) is the sum of an even function f_E(x) and an odd function f_O(x), then show that
f_E(x) = (f(x)+f(-x))/2 and f_O(x) = (f(x)-f(-x))/2

Verified step by step guidance
1
Recall the definitions of even and odd functions: an even function satisfies \(f_E(x) = f_E(-x)\), and an odd function satisfies \(f_O(x) = -f_O(-x)\).
Given that \(f(x) = f_E(x) + f_O(x)\), write the expression for \(f(-x)\) by substituting \(-x\) into the function: \(f(-x) = f_E(-x) + f_O(-x)\).
Use the properties of even and odd functions to rewrite \(f(-x)\) as \(f(-x) = f_E(x) - f_O(x)\), since \(f_E(-x) = f_E(x)\) and \(f_O(-x) = -f_O(x)\).
Add the two equations \(f(x) = f_E(x) + f_O(x)\) and \(f(-x) = f_E(x) - f_O(x)\) to isolate \(f_E(x)\): \(f(x) + f(-x) = 2 f_E(x)\).
Similarly, subtract \(f(-x)\) from \(f(x)\) to isolate \(f_O(x)\): \(f(x) - f(-x) = 2 f_O(x)\). Then solve for \(f_E(x)\) and \(f_O(x)\) to get \(f_E(x) = \frac{f(x) + f(-x)}{2}\) and \(f_O(x) = \frac{f(x) - f(-x)}{2}\).

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Even and Odd Functions

An even function satisfies f(x) = f(-x) for all x, meaning its graph is symmetric about the y-axis. An odd function satisfies f(-x) = -f(x), showing symmetry about the origin. Understanding these definitions is essential to decompose any function into even and odd parts.
Recommended video:
06:21
Properties of Functions

Function Decomposition

Any function f(x) can be expressed as the sum of an even function f_E(x) and an odd function f_O(x). This decomposition helps analyze the function's symmetry properties and simplifies integration and other operations by separating symmetric components.
Recommended video:
10:07
Partial Fraction Decomposition: Distinct Linear Factors

Algebraic Manipulation for Decomposition

To find f_E(x) and f_O(x), use the definitions of even and odd functions to form equations involving f(x) and f(-x). Adding and subtracting these equations isolates the even and odd parts, leading to the formulas f_E(x) = (f(x)+f(-x))/2 and f_O(x) = (f(x)-f(-x))/2.
Recommended video:
05:25
Determine Continuity Algebraically