Chapter 1: Problem 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 neither even nor odd.
Step by step solution
01
Understand the Function
The function given is \(f(x) = x|x|\). The term \(|x|\) represents the absolute value of \(x\), which is \(x\) if \(x \geq 0\) and \(-x\) if \(x < 0\). Combine these regions with \(x\) as given in the function.
02
Verify Symmetry for Even Function
A function is even if \(f(-x) = f(x)\) for all \(x\) in the domain. Replace \(x\) by \(-x\) in the function: \(f(-x) = (-x)|-x| = x|x|\) because \(|-x| = x\). Hence, \(f(-x) = x(x) = x^2\). This is not equal to \(f(x) = x|x|\) for all \(x\). Thus, the function is not even.
03
Verify Symmetry for Odd Function
A function is odd if \(f(-x) = -f(x)\) for all \(x\). We already calculated \(f(-x) = x^2\). Now, \(-f(x) = -(x|x|)\). For positive \(x\), this becomes \(-x^2\), and for negative \(x\), this becomes \(x^2\), which is \(-f(x) = x|x|\). These do not satisfy \(f(-x) = -f(x)\) for all \(x\). Thus, the function is not odd.
04
Conclusion
Since the function is neither even nor odd based on the checks in Steps 2 and 3, conclude \(f(x) = x|x|\) is neither even nor odd.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Symmetry
When exploring mathematical functions, symmetry is a key concept in determining whether a function is even or odd. A function is said to be symmetric if it maintains certain properties when its input is altered in a specific way.
- An even function exhibits symmetry about the y-axis. This means that for every point \(x, y\) on the graph of the function, there is a corresponding point \(-x, y\) with the same y-value. This symmetry can be mathematically expressed as \(f(-x) = f(x)\).
- An odd function shows rotational symmetry about the origin, implying that for every point \(x, y\) on the graph, there is a corresponding point \(-x, -y\) that creates a mirror image through the origin. The condition for a function to be odd is given by \(f(-x) = -f(x)\).
Absolute Value Function
The absolute value function, denoted as \(|x|\), is a fundamental concept in mathematics. It represents the distance of a number from zero on the number line, thereby always producing a non-negative result.
- If \(x \geq 0\), then we have \(|x| = x\), thus the value remains unchanged.
- If \(x < 0\), then \(|x| = -x\), effectively reflecting the negative value to its positive counterpart.
Function Analysis
Function analysis involves examining the properties and behavior of a given function. It includes determining attributes such as evenness, oddness, domain, range, and intercepts.
- For \(f(x) = x|x|\), testing for evenness involves checking if \(f(x)\) equals \(f(-x)\). Substituting \(-x\) yields \(f(-x) = x|x|\), which is not the same as \(f(x) = x|x|\) for all \(x\), proving the function is not even.
- For oddness, you'd verify \(f(-x) = -f(x)\). From our solutions, calculating \(-f(x)\) does not equate with \(f(-x)\) for every \(x\), discounting it as an odd function.