Chapter 2: Problem 9
In Exercises \(1-20\), determine whether the given limit exists. If it does exist, then compute it. $$ \lim _{x \rightarrow 1^{+}} \frac{1}{\sqrt{x-1}} $$
Short Answer
Expert verified
The limit does not exist as a finite number; it is \(+\infty\).
Step by step solution
01
Understanding the Limit
The expression given is \( \lim_{x \rightarrow 1^{+}} \frac{1}{\sqrt{x-1}} \). This means we want to find the limit of the function as \( x \) approaches 1 from the right. From the right implies that \( x \) is slightly greater than 1.
02
Exploring the Function
Consider \( x - 1 \) for values just greater than 1. As \( x \rightarrow 1^{+} \), the term \( x-1 \) becomes a very small positive number, approaching 0 from the positive side.
03
Evaluating the Square Root in the Denominator
As \( x \rightarrow 1^{+} \), \( \sqrt{x-1} \) becomes \( \sqrt{0^{+}} \), which is a very small positive number. The expression \( \sqrt{x-1} \) approaches 0 but remains positive.
04
Considering the Behavior of the Reciprocal
Since \( \sqrt{x-1} \) approaches 0 from the positive side, \( \frac{1}{\sqrt{x-1}} \) will tend to infinity, because the reciprocal of a very small positive number is very large. Therefore, \( \lim_{x \rightarrow 1^{+}} \frac{1}{\sqrt{x-1}} = +\infty \).
05
Concluding the Limit
The limit does not exist as a finite number since it approaches infinity. In terms of mathematical limits, since it tends toward positive infinity, it is typically described as \( +\infty \), indicating a vertical asymptote at \( x = 1 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
One-Sided Limits
One-sided limits are a fundamental concept in calculus. They help us understand the behavior of a function as it approaches a specific point from one direction, either from the left or the right. In the context of the original exercise, the notation \( \lim_{x \rightarrow 1^{+}} \) specifies a one-sided limit. The \( 1^{+} \) indicates that we are interested in the limit of \( x \) approaching 1 from the right side. This means \( x \) is slightly greater than 1 as it approaches 1.
The concept of one-sided limits allows us to study the continuity and behavior of functions in detail. This is particularly useful if the function behaves differently when approaching a point from different directions. "One-sided" here signifies that we are not considering what happens on both sides at once, but rather focusing on one direction.
Overall, understanding one-sided limits is important for analyzing functions where there could be a break in the graph, such as at a jump or vertical asymptote.
The concept of one-sided limits allows us to study the continuity and behavior of functions in detail. This is particularly useful if the function behaves differently when approaching a point from different directions. "One-sided" here signifies that we are not considering what happens on both sides at once, but rather focusing on one direction.
Overall, understanding one-sided limits is important for analyzing functions where there could be a break in the graph, such as at a jump or vertical asymptote.
Infinite Limits
Infinite limits occur when the value of a function increases or decreases without bound as it approaches a certain point. In the given exercise, as \( x \) approaches 1 from the right, the value of \( \frac{1}{\sqrt{x-1}} \) becomes extremely large. This behavior describes what is called an infinite limit.
Since \( \sqrt{x-1} \to 0^{+} \), the denominator of the function approaches zero from the positive side. This makes the fraction \( \frac{1}{\sqrt{x-1}} \) grow larger, resulting in an infinite limit. When we say a function tends to infinity, it signifies that the outputs become indefinitely large as the input approaches the specified point.
Since \( \sqrt{x-1} \to 0^{+} \), the denominator of the function approaches zero from the positive side. This makes the fraction \( \frac{1}{\sqrt{x-1}} \) grow larger, resulting in an infinite limit. When we say a function tends to infinity, it signifies that the outputs become indefinitely large as the input approaches the specified point.
- If the limit approaches positive infinity, we denote it as \( +\infty \).
- If it approaches negative infinity, we denote it as \( -\infty \).
Vertical Asymptotes
Vertical asymptotes are specific lines on a graph where the function tends towards infinity. These occur when a function's limit approaches infinity from one or both sides as \( x \) approaches a certain value. In the context of the exercise, there is a vertical asymptote at \( x = 1 \) because \( \lim_{x \rightarrow 1^{+}} \frac{1}{\sqrt{x-1}} = +\infty \).
Key characteristics of vertical asymptotes include:
Key characteristics of vertical asymptotes include:
- The graph of the function will continue upwards or downwards without bounds near the asymptote, but will never actually touch or cross it.
- It usually occurs where a function has a division by zero in the limit.