Chapter 2: Problem 19
Find the limits. \(\lim _{x \rightarrow \infty} \frac{2 x+1}{\sqrt{x^{2}+3}}\)
Short Answer
Expert verified
The limit as \( x \to \infty \) is 2.
Step by step solution
01
Analyze the Expression
The given limit is \( \lim_{x \to \infty} \frac{2x + 1}{\sqrt{x^2 + 3}} \). We notice that both the numerator and the denominator involve terms with \( x \), where \( 2x \) and \( \sqrt{x^2} \) are dominant as \( x \to \infty \).
02
Simplify the Expression
Factor out \( x \) from the square root in the denominator. This gives us \( \sqrt{x^2 + 3} = x \sqrt{1 + \frac{3}{x^2}} \). Now the expression becomes:\[\frac{2x + 1}{x \sqrt{1 + \frac{3}{x^2}}}\]
03
Divide Terms by x
Divide each term in the fraction by \( x \):\[\frac{2x + 1}{x \sqrt{1 + \frac{3}{x^2}}} = \frac{2 + \frac{1}{x}}{\sqrt{1 + \frac{3}{x^2}}}\]
04
Consider the Limit as x Approaches Infinity
As \( x \to \infty \), the terms \( \frac{1}{x} \) and \( \frac{3}{x^2} \) approach 0. Thus, the expression simplifies to:\[\frac{2 + 0}{\sqrt{1 + 0}} = \frac{2}{1} = 2\]
05
Conclusion: Evaluate the Limit
The limit evaluates to 2 as \( x \to \infty \). Therefore, the solution is \( \lim_{x \to \infty} \frac{2x + 1}{\sqrt{x^2 + 3}} = 2 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Asymptotic Behavior
Asymptotic Behavior is about understanding how a function behaves as the variable approaches a certain value, often infinity or zero. In this problem, since we are evaluating the limit as \( x \) approaches infinity, we focus on how the expression \( \frac{2x + 1}{\sqrt{x^2 + 3}} \) behaves as \( x \) gets extremely large.
In such cases, it is crucial to identify the leading or dominant terms. These dominate the behavior of the function when \( x \) is large. Here, for instance, \( 2x \) in the numerator and \( \sqrt{x^2} \) or basically \( x \) in the denominator are dominant. Thus, often other smaller terms become negligible as \( x \) reaches infinity.
In such cases, it is crucial to identify the leading or dominant terms. These dominate the behavior of the function when \( x \) is large. Here, for instance, \( 2x \) in the numerator and \( \sqrt{x^2} \) or basically \( x \) in the denominator are dominant. Thus, often other smaller terms become negligible as \( x \) reaches infinity.
- This simplification helps us predict that the behavior of the function predominantly depends on these dominant terms.
- In practical terms, an asymptotic behavior examines the trend. It ignores minor fluctuations which are negligible when compared to dominant terms.
- This is why, in the solution, terms like \( \frac{1}{x} \) or \( \frac{3}{x^2} \) tend to vanish as \( x \to \infty \) because they become infinitesimally small compared to \( x \) or \( x^2 \).
Dominant Terms
Dominant Terms are those parts of an expression that take over the behavior of the function as the variable grows larger and larger. When finding limits as \( x \to \infty \), dominant terms largely control the outcome.
In the expression \( \frac{2x + 1}{\sqrt{x^2 + 3}} \), we need to simplify to identify these main terms.
\[\frac{2x}{x} = 2\]
In the expression \( \frac{2x + 1}{\sqrt{x^2 + 3}} \), we need to simplify to identify these main terms.
- In the numerator, the term \( 2x \) grows without bounds as \( x \to \infty \), overshadowing the constant \( +1 \).
- In the denominator, \( \sqrt{x^2 + 3} \) becomes dominated by \( \sqrt{x^2} = x \), because \( 3 \) becomes minuscule compared to \( x^2 \) when \( x \) is large.
\[\frac{2x}{x} = 2\]
Infinity Analysis
Infinity Analysis focuses on how functions behave as the input grows without bound. It's a technique inherent in calculus that provides insights into the eventual steady state or asymptotic trend of a function.
When conducting infinity analysis in the given exercise, we're looking to simplify the expression \( \frac{2x + 1}{\sqrt{x^2 + 3}} \) to make it easier to handle at \( x = \infty \). This involves reducing the expression and paying special attention to terms that diminish in effect as \( x \) increases.
When conducting infinity analysis in the given exercise, we're looking to simplify the expression \( \frac{2x + 1}{\sqrt{x^2 + 3}} \) to make it easier to handle at \( x = \infty \). This involves reducing the expression and paying special attention to terms that diminish in effect as \( x \) increases.
- The variable \( x \) in this context represents a journey towards infinity. During this journey, terms like \( \frac{1}{x} \) and \( \frac{3}{x^2} \) shrink into nothingness, allowing the dominant terms to take over.
- Through simplification from \( \frac{2 + \frac{1}{x}}{\sqrt{1 + \frac{3}{x^2}}} \) as \( x \to \infty \), smaller terms drop away. This leaves us with the limit of \( \frac{2}{1} \).