Chapter 1: Problem 27
Find the limits. $$ \lim _{x \rightarrow 2^{+}} \frac{1}{|2-x|} $$
Short Answer
Expert verified
The limit is \(+\infty\).
Step by step solution
01
Understanding the Limit Notation
The limit \( \lim_{x \to 2^+} \frac{1}{|2-x|} \) requires us to evaluate the behavior of the expression as \( x \) approaches 2 from the right. This means \( x \) is slightly greater than 2.
02
Analyze the Absolute Value
For \( x \to 2^+ \), \( x - 2 = \epsilon \) where \( \epsilon > 0 \), thus \(|2-x| = |-(x-2)| = \epsilon \). The expression simplifies to \( \frac{1}{\epsilon} \) as \( \epsilon \to 0^+ \).
03
Evaluate the Limit Behavior
As \( \epsilon \to 0^+ \), \( \frac{1}{\epsilon} \to \infty \). This indicates that the expression becomes very large approaching infinity as \( x \to 2^+ \).
04
Conclusion of the Limit
Since \( \frac{1}{\epsilon} \to \infty \), the limit of the given expression as \( x \to 2^+ \) is \( +\infty \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Limit Behavior
When we talk about limit behavior, we're interested in what happens to a function as a variable approaches a certain value. In this case, we're examining the limit of the function \( \frac{1}{|2-x|} \) as \( x \) gets closer to 2 from the right-hand side. This means we are interested in the behavior of the function as the values of \( x \) are slightly greater than 2.
To understand this, consider that if \( x \) approaches 2, it means that \( x \) is not exactly 2, but very close to it. The term "from the right", denoted by \( x \to 2^+ \), specifies that \( x \) is approaching 2 from values larger than 2. As a result of this approach, we want to understand how the function behaves - whether it increases, decreases, or becomes undefined at some point.
In our example, as \( x \) approaches 2 from the right, the distance \( x - 2 \) (a small positive number) affects how the function behaves since this distance is in the denominator of our function. As this distance gets exceedingly small, the reciprocal of a very small number becomes very large. Thus, as \( x \to 2^+ \), the behavior of the function is to grow towards \( +\infty \).
To understand this, consider that if \( x \) approaches 2, it means that \( x \) is not exactly 2, but very close to it. The term "from the right", denoted by \( x \to 2^+ \), specifies that \( x \) is approaching 2 from values larger than 2. As a result of this approach, we want to understand how the function behaves - whether it increases, decreases, or becomes undefined at some point.
In our example, as \( x \) approaches 2 from the right, the distance \( x - 2 \) (a small positive number) affects how the function behaves since this distance is in the denominator of our function. As this distance gets exceedingly small, the reciprocal of a very small number becomes very large. Thus, as \( x \to 2^+ \), the behavior of the function is to grow towards \( +\infty \).
Absolute Value
Understanding absolute value is crucial when working with limits, especially when it involves expressions like \( |2-x| \). Absolute value gives us a measure of distance a number is from zero on the number line, regardless of direction. So, \( |a| \) is the same whether \( a \) is positive or negative, since it only considers the magnitude, not the sign.
In our specific problem, the expression inside the absolute value \( 2-x \) becomes important. When \( x \) approaches 2 from the right, \( x \) is greater than 2, meaning \( 2-x \) is negative. That’s why we can rewrite \( |2-x| \) as \(|-(x-2)|\).
In our specific problem, the expression inside the absolute value \( 2-x \) becomes important. When \( x \) approaches 2 from the right, \( x \) is greater than 2, meaning \( 2-x \) is negative. That’s why we can rewrite \( |2-x| \) as \(|-(x-2)|\).
- For \( x > 2 \): \( 2-x \) is negative, hence \( |2-x| = -(2-x) = x-2 \).
- This turns our expression into \( \frac{1}{x-2} \), where \( x-2 \) is simply the positive \( \epsilon \) we talked about earlier.
Right-Hand Limit
A right-hand limit specifically refers to the behavior of a function as the variable approaches a certain value from the right. In mathematical notation, \( \lim_{x \to 2^+} \) indicates that \( x \) is approaching 2 from numbers slightly larger than 2.
This right-sided approach focuses solely on one direction of movement towards the limit point, providing insights into how a function behaves under these conditions. It’s particularly useful in understanding the structure of discontinuities or points where a function might explode to infinity.
This right-sided approach focuses solely on one direction of movement towards the limit point, providing insights into how a function behaves under these conditions. It’s particularly useful in understanding the structure of discontinuities or points where a function might explode to infinity.
- For our function \( \frac{1}{|2-x|} \), the right-hand limit asks us to exclusively consider \( x \) values over 2, thus emphasizing \( x - 2 \) being a tiny positive number.
- This results in a very small denominator getting closer and closer to zero from a positive direction, causing the overall expression to increase without bound, moving towards \( +\infty \).