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Ch. 2 - Graphs and Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 3, Problem 63

Determine whether each function is even, odd, or neither. ƒ(x)=x+1/x5

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Recall the definitions: A function \( f(x) \) is even if \( f(-x) = f(x) \) for all \( x \), and it is odd if \( f(-x) = -f(x) \) for all \( x \). If neither condition holds, the function is neither even nor odd.
Given the function \( f(x) = x + \frac{1}{x^5} \), start by finding \( f(-x) \). Substitute \( -x \) into the function:
\[ f(-x) = (-x) + \frac{1}{(-x)^5} \]
Simplify the expression for \( f(-x) \). Remember that \( (-x)^5 = -x^5 \) because an odd power preserves the negative sign:
\[ f(-x) = -x + \frac{1}{-x^5} = -x - \frac{1}{x^5} \]
Compare \( f(-x) \) with \( f(x) \) and \( -f(x) \): \( f(x) = x + \frac{1}{x^5} \) and \( -f(x) = -x - \frac{1}{x^5} \). Since \( f(-x) = -f(x) \), the function \( f(x) \) is odd.

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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 in its domain, meaning its graph is symmetric about the y-axis. An odd function satisfies f(-x) = -f(x), showing symmetry about the origin. Determining whether a function is even, odd, or neither involves testing these conditions.
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Function Substitution

To test if a function is even or odd, substitute -x into the function in place of x. Simplify the resulting expression and compare it to the original function f(x) and its negative -f(x). This substitution is key to identifying symmetry properties.
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Properties of Exponents and Algebraic Simplification

Understanding how to manipulate expressions with exponents, especially negative and fractional powers, is essential. Simplifying terms like (−x)^5 or 1/(−x)^5 correctly helps in comparing f(-x) with f(x) or -f(x) accurately.
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