Chapter 1: Problem 68
\(65-70\) Determine whether \(f\) is even, odd, or neither. If you have a graphing calculator, use it to check your answer visually. $$f(x)=x|x|$$
Short Answer
Expert verified
The function is odd.
Step by step solution
01
Understand the definition of even and odd functions
A function is even if for every x in the domain, \(f(-x) = f(x)\). A function is odd if for every x in the domain, \(f(-x) = -f(x)\). If neither condition holds, the function is neither even nor odd.
02
Find the negative of the input
Replace \(x\) with \(-x\) in the function to consider the negative input:\[f(-x) = -x|-x|.\] Compute this expression to further determine its nature.
03
Simplify the expression for negative input
Since \(-x\) will be negative when \(x\) is positive, the absolute value \(|-x| = x\), therefore: \[f(-x) = -x|x| = -(x|x|).\] Thus, \(f(-x) = -f(x)\).
04
Determine the function's parity
Since \(f(-x) = -f(x)\), the function \(f(x) = x|x|\) is odd.
05
Confirm the solution using a graphing tool
Use a graphing calculator to plot \(f(x) = x|x|\). The graph should be symmetric about the origin, confirming that the function is odd.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Even Function
An even function is one where the graph has symmetry about the y-axis. This symmetry means that for every point \(x, f(x)\) on the graph, there is a corresponding point \(-x, f(x)\). So, visually, if you were to fold the graph along the y-axis, both sides would match perfectly.
To mathematically confirm if a function is even, you check the formula \(f(-x) = f(x)\). If this equality holds for all x in the domain, then the function is even. Common examples include \(f(x) = x^2\) and \(f(x) = \cos(x)\). These functions exhibit y-axis symmetry and satisfy the condition of being even.
To mathematically confirm if a function is even, you check the formula \(f(-x) = f(x)\). If this equality holds for all x in the domain, then the function is even. Common examples include \(f(x) = x^2\) and \(f(x) = \cos(x)\). These functions exhibit y-axis symmetry and satisfy the condition of being even.
Absolute Value
The absolute value of a number is its distance from zero on the number line, regardless of direction. It is always non-negative. The absolute value is denoted as \(|x|\). For instance:
- \(|5| = 5\)
- \(|-3| = 3\)
Function Symmetry
Function symmetry is a powerful concept in understanding how functions behave. Two major types of symmetry exist:
- **Y-axis symmetry** suggests that a function is even. This means the graph looks the same on both sides of the y-axis.
- **Origin symmetry** is characteristic of odd functions. This means that rotating the graph by 180° about the origin results in the same graph.
Graphing Calculator
A graphing calculator is a tool that can visually confirm the nature of a function. By plotting \(f(x) = x|x|\) on a graphing calculator, you can check for symmetry. For odd functions, like in the current analysis, the graph should show symmetry about the origin.
Using a graphing calculator to visualize functions gives quick insights into their nature. It supports analytical results by providing a graphical representation, making it easier to see complex behaviors. This visual approach aids in confirming mathematical properties determined through algebra, such as whether a function is even, odd, or neither.
Using a graphing calculator to visualize functions gives quick insights into their nature. It supports analytical results by providing a graphical representation, making it easier to see complex behaviors. This visual approach aids in confirming mathematical properties determined through algebra, such as whether a function is even, odd, or neither.