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Ch. 1 - Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Not the one you use?Change textbook
Chapter 1, Problem 1.1.52

Even and Odd Functions


In Exercises 47–62, say whether the function is even, odd, or neither. Give reasons for your answer.


g(x) = x⁴ + 3x² − 1

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1
To determine if a function is even, odd, or neither, we need to analyze the function's symmetry properties. A function g(x) is even if g(-x) = g(x) for all x in the domain, and it is odd if g(-x) = -g(x) for all x in the domain.
Start by substituting -x into the function g(x) = x⁴ + 3x² − 1 to find g(-x). This gives us g(-x) = (-x)⁴ + 3(-x)² − 1.
Simplify the expression for g(-x). Since (-x)⁴ = x⁴ and (-x)² = x², we have g(-x) = x⁴ + 3x² − 1.
Compare g(-x) with g(x). We find that g(-x) = x⁴ + 3x² − 1 is exactly the same as g(x) = x⁴ + 3x² − 1, which means g(-x) = g(x).
Since g(-x) = g(x), the function g(x) is even. Therefore, g(x) = x⁴ + 3x² − 1 is an even function.

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Key Concepts

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

Even Functions

A function is classified as even if it satisfies the condition f(-x) = f(x) for all x in its domain. This means that the graph of an even function is symmetric with respect to the y-axis. Common examples include polynomial functions with only even powers of x, such as x² or x⁴.
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Odd Functions

A function is considered odd if it meets the condition f(-x) = -f(x) for all x in its domain. This indicates that the graph of an odd function is symmetric with respect to the origin. Typical examples include polynomial functions with only odd powers of x, like x³ or x⁵.
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Neither Even Nor Odd Functions

A function is classified as neither even nor odd if it does not satisfy the conditions for either classification. This can occur when a function contains both even and odd powers of x or does not exhibit symmetry about the y-axis or the origin. Analyzing the function's behavior at -x compared to x helps determine this classification.
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