Chapter 1: Problem 36
For each function, find the largest possible domain and determine the range. $$ f(x)=\frac{1}{x^{2}+1} $$
Short Answer
Expert verified
Domain: \((-\infty, \infty)\), Range: \((0, 1]\).
Step by step solution
01
Identify the Restrictions for the Domain
For the function \( f(x) = \frac{1}{x^2 + 1} \), we need to determine the values of \( x \) for which the function is defined. The primary concern is ensuring that the denominator is not equal to zero. Since \( x^2 + 1 \geq 1 \) for all real numbers \( x \), the denominator is never zero. Therefore, there are no restrictions on \( x \).
02
State the Largest Possible Domain
Given that \( x^2 + 1 \) is never zero, the function \( f(x) = \frac{1}{x^2 + 1} \) is defined for all real numbers \( x \). Thus, the largest possible domain is all real numbers, \( (-\infty, \infty) \).
03
Determine the Range by Analyzing the Function
To find the range, evaluate the behavior of \( f(x) = \frac{1}{x^2 + 1} \). Note that \( x^2 \geq 0 \) implies \( x^2 + 1 \geq 1 \). This makes \( f(x) \) always less than or equal to \( 1 \). Since \( x^2 \) is non-negative and \( f(x) = \frac{1}{x^2 + 1} \) never reaches zero, it approaches \( 0 \) as \( x^2 \) becomes very large.
04
Express the Range
The function values \( f(x) = \frac{1}{x^2 + 1} \) can never actually reach zero but can get arbitrarily close to it. Therefore, the range of the function is \((0, 1]\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Domain
The domain of a function refers to the set of all possible input values (or x-values) for which the function is defined. When determining the domain, we look for any restrictions that might prevent an x-value from being permissible. For rational functions, like the function given \[ f(x) = \frac{1}{x^2 + 1} \], we focus on ensuring the denominator is not zero because division by zero is undefined in mathematics. However, for \( x^2 + 1 \), no real number will make the denominator zero, since \( x^2 \) is always non-negative and adding 1 guarantees a positive outcome. Thus, the largest possible domain for this function includes all real numbers.
- Rational functions are expressions that are the ratio of two polynomials.
- The domain is determined by where the denominator does not equal zero.
- For \( f(x) = \frac{1}{x^2 + 1} \), the domain is all real numbers \((-\infty, \infty)\).
Function Range
The range of a function represents the set of all possible output values (or y-values). To find this, we analyze the behavior of the function across its domain. For the function \( f(x) = \frac{1}{x^2 + 1} \), the key observation is that the denominator \( x^2 + 1 \) is always greater than or equal to 1. Hence, the maximum value that \( f(x) \) can achieve is 1, which occurs when \( x = 0 \). As \( x \) moves away from zero, \( x^2 + 1 \) grows larger, making \( f(x) \) approach but never reach zero. This gives us the range as \( (0, 1] \).
- The range is the set of all possible values that the function can output.
- By analyzing the function \( f(x) = \frac{1}{x^2 + 1} \), we see that it approaches zero but reaches up to 1.
- Therefore, the range is \( (0, 1] \).
Rational Functions
Rational functions are expressions that involve ratios of polynomials, such as \( f(x) = \frac{1}{x^2 + 1} \). Understanding how they work is pivotal in calculus and algebra.Characteristics of Rational Functions:
- Rational functions are defined as the quotient of two polynomials. The numerator and denominator coefficients are both polynomials.
- The domain of a rational function is all real numbers, except where the denominator is zero.
- The range is determined by the possible outputs based on input values, considering asymptotics and intercepts.
- Graphing helps visualize asymptotes and intercepts, revealing behavior such as approach to certain lines or values.