Chapter 9: Problem 21
Determine whether each function is one-to-one. $$ f(x)=x^{4} $$
Short Answer
Expert verified
The function \(f(x) = x^4\) is not one-to-one.
Step by step solution
01
Understanding One-to-One Function
A function is considered one-to-one if every output corresponds to exactly one input. In mathematical terms, a function is one-to-one if for all pairs of inputs \(x_1\) and \(x_2\), whenever \(f(x_1) = f(x_2)\) implies that \(x_1 = x_2\). We need to check if this condition holds for \(f(x) = x^4\).
02
Testing the Function Property
Consider two arbitrary inputs \(x_1\) and \(x_2\). We need to investigate the situation \(f(x_1) = f(x_2)\), which implies \(x_1^4 = x_2^4\). Is the only possible conclusion \(x_1 = x_2\)?
03
Analyzing Equality of Powers
Given \(x_1^4 = x_2^4\), we must determine whether \(x_1 = x_2\) with certainty. Notice that \(x_1^2 = x_2^2\), which means either \(x_1 = x_2\) or \(x_1 = -x_2\).
04
Conclusion on One-to-One Property
Since \(x_1^4 = x_2^4\) leads not only to \(x_1 = x_2\) but also to \(x_1 = -x_2\), the function is not one-to-one. Multiple inputs (e.g., 2 and -2) yield the same output (16).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Analysis
Function analysis involves investigating the properties and behavior of a function, such as its domain, range, and whether it is one-to-one. To determine if a function is one-to-one, you must check if every entry in the domain maps to a unique output in the range. This analysis requires understanding the concept of injectivity, which is a mathematical condition where different inputs always result in different outputs.
In the exercise with the function \(f(x) = x^4\), function analysis helps identify potential pairs of different inputs that lead to the same output, like \(2\) and \(-2\). Such insights guide us towards recognizing whether the function's input-output relationship satisfies the one-to-one function criteria.
In the exercise with the function \(f(x) = x^4\), function analysis helps identify potential pairs of different inputs that lead to the same output, like \(2\) and \(-2\). Such insights guide us towards recognizing whether the function's input-output relationship satisfies the one-to-one function criteria.
Mathematical Functions
Mathematical functions are relationships where each input in a set is associated with exactly one output. When discussing specific functions like \(f(x) = x^4\), it helps to recall basic properties:
- The domain is the set of all possible inputs, usually all real numbers for functions like polynomials.
- The range consists of all outputs the function can produce, which, in this case, is non-negative real numbers as the square of a number is always non-negative.
Interpreting Function Behavior
Interpreting the behavior of a function involves examining how it behaves across its domain. For instance, we can graph \(f(x) = x^4\) to visually explore how inputs map to outputs. The function's plot reveals that it forms a 'U' shape, where both positive and negative inputs yield the same positive output.
This mirrored symmetry around the y-axis underpins the function not being one-to-one.
This mirrored symmetry around the y-axis underpins the function not being one-to-one.
- Visual patterns from graphs highlight output repetition for different inputs.
- Such behaviors are critical in distinguishing between one-to-one and non-one-to-one functions.