Chapter 3: Problem 52
Determine whether the function is odd, even, or neither. $$h(x)=2 x-x^{3}$$
Short Answer
Expert verified
The function \( h(x) = 2x - x^3 \) is odd.
Step by step solution
01
Understand Definitions
An even function is symmetrical around the y-axis, which means that \( f(-x) = f(x) \) for all \( x \). An odd function is symmetrical around the origin, which means that \( f(-x) = -f(x) \) for all \( x \). Functions that do not meet either condition are neither even nor odd.
02
Compute \( h(-x) \)
To determine if the function is even or odd, calculate \( h(-x) \). Given \( h(x) = 2x - x^3 \), substitute \(-x\) for \(x\):\[h(-x) = 2(-x) - (-x)^3 = -2x + x^3\]
03
Compare \( h(-x) \) with \( h(x) \) and \(-h(x)\)
Compare \( h(-x) \) with \( h(x) \) and \(-h(x)\):- \( h(x) = 2x - x^3 \)- \( h(-x) = -2x + x^3 \)- \(-h(x) = -(2x - x^3) = -2x + x^3 \)Notice, \( h(-x) = -h(x) \).
04
Conclusion based on Symmetry
Since \( h(-x) = -h(x) \), the function is odd because it is symmetric about the origin.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exploring Function Symmetry
Symmetry in functions refers to the visual balance of a function's graph with respect to certain lines or points. When analyzing function symmetry, there are two main types to consider:
- Symmetry about the y-axis: This is characteristic of even functions. If you fold the graph along the y-axis, both halves would match perfectly. Algebraically, this means for a function \( f(x) \), we have \( f(-x) = f(x) \) for all x.
- Symmetry about the origin: Found in odd functions, this type of symmetry results in a graph that can be rotated 180 degrees around the origin and still look the same. For odd functions, the algebraic condition is \( f(-x) = -f(x) \).
Function Analysis for Identifying Symmetry
Function analysis refers to the process of studying and understanding the nature of a function, including its symmetry, growth, and behavior. When specifically identifying symmetry, function analysis focuses on computing values and substitutions to compare original and modified functions.For instance, given a function \( h(x) = 2x - x^3 \), one can perform the following steps to determine its symmetry:- Compute \( h(-x) \): Substitute \(-x\) into the function. For our example, \[ h(-x) = 2(-x) - (-x)^3 = -2x + x^3. \]- Compare \( h(-x) \) to \( h(x) \): Check if \( h(-x) = h(x) \). This would imply an even function, which does not hold here.- Compare \( h(-x) \) to \(-h(x)\): Verify if \( h(-x) = -h(x) \). If true, as in this example, it confirms odd symmetry as the conditions align, proving the function to be odd.Through systematic function analysis, one effectively determines the odd or even nature of a function by leveraging these comparisons. This method involves simplicity and logic, allowing students to grasp fundamental insights into functions' properties.
Understanding Polynomial Functions
A polynomial function is a mathematical expression involving a sum of powers in one or more variables, multiplied by coefficients. These types of functions are prevalent in mathematics and are expressed in the form:\[ f(x) = a_nx^n + a_{n-1}x^{n-1} + \, ... \, + a_1x + a_0 \]where \( a_n, a_{n-1}, \ldots, a_0 \) are constants and \( n \) is a non-negative integer.Key aspects of polynomial functions include:
- The degree: The highest power of \( x \) with a non-zero coefficient. It often determines the end behavior and symmetry properties of the function.
- Coefficients: These can change the shape and position of the graph. For instance, in \( h(x) = 2x - x^3 \), coefficients 2 and -1 affect the slope and direction of the graph.