Chapter 5: Problem 29
Compute, if possible, the one-sided limits of the function $$ f(x)=e^{1 / x} $$ at \(0 .\)
Short Answer
Expert verified
Right-hand limit is \( \infty \) and left-hand limit is 0; the two-sided limit at 0 does not exist.
Step by step solution
01
Understand the One-Sided Limits
To solve the problem, we'll need to compute the two one-sided limits: the limit of \( f(x) = e^{1/x} \) as \( x \) approaches 0 from the positive side (right-hand limit) and from the negative side (left-hand limit).
02
Compute the Right-Hand Limit
To find \( \lim_{x \to 0^+} e^{1/x} \), observe that as \( x \) approaches 0 from the positive side, \( 1/x \) goes to \(+\infty\). Consequently, \( e^{1/x} \) goes to \( e^{+\infty} = \infty \). Thus, the right-hand limit is \( \infty \).
03
Compute the Left-Hand Limit
For \( \lim_{x \to 0^-} e^{1/x} \), as \( x \) approaches 0 from the negative side, \( 1/x \) goes to \(-\infty\). Hence, \( e^{1/x} \) tends to \( e^{-\infty} = 0 \). Thus, the left-hand limit is 0.
04
Conclude about the Possibility of Limit
Since the right-hand limit is \( \infty \) and the left-hand limit is \( 0 \), the one-sided limits are not equal. Therefore, the two-sided limit as \( x \) approaches 0 does not exist.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Right-Hand Limit
When we look at a function's behavior as it approaches a certain point from the right side, we're finding its right-hand limit. This is denoted as \( \lim_{x \to c^+} f(x) \), where "\(+\)" signifies that \(x\) approaches \(c\) from values greater than \(c\). For the function \(f(x) = e^{1/x}\), as \(x\) approaches 0 from the positive side, the term \(1/x\) becomes very large, or tends towards \(+\infty\). As a result, \(e^{1/x}\) also becomes very large because exponential functions increase rapidly when their exponent values increase. Therefore, in this scenario, the right-hand limit of the function as \(x\) approaches 0 is \(\infty\).
This tells us: - As we approach 0 from the right, \(e^{1/x}\) shoots towards infinity. - This behavior makes it clear that the function does not settle towards a finite number on this side.
This tells us: - As we approach 0 from the right, \(e^{1/x}\) shoots towards infinity. - This behavior makes it clear that the function does not settle towards a finite number on this side.
Left-Hand Limit
The left-hand limit looks at how a function behaves when approaching a point from the left side, or from values smaller than \(c\). It's represented as \( \lim_{x \to c^-} f(x) \). For \(f(x) = e^{1/x}\), as \(x\) approaches 0 from the negative side, the expression \(1/x\) becomes largely negative, driving \(e^{1/x}\) towards \(e^{-fty}\). Exponential functions approach zero when their exponents decrease towards \(-\infty\). Thus, the left-hand limit of this function as \(x\) tends to 0 is 0.
Here's what this outcome means: - Approaching 0 from the left, \(e^{1/x}\) gets closer and closer to zero. - Contrasting with the right-hand limit, this shows a drastically different behavior on this side.
Here's what this outcome means: - Approaching 0 from the left, \(e^{1/x}\) gets closer and closer to zero. - Contrasting with the right-hand limit, this shows a drastically different behavior on this side.
Exponential Function
Exponential functions, in general, behave distinctively based on their exponential expressions. For \(f(x) = e^{1/x}\), the base \(e\) is a constant approximately equal to 2.718, and it's raised to a power determined by the fractional expression \(1/x\). Its behavior shifts significantly depending on whether \(1/x\) becomes positive or negative:
- **Positive Exponent**: If \(1/x\) is positive, \(e^{1/x}\) escalates sharply, as we observed with the right-hand limit moving to \(+\infty\). - **Negative Exponent**: When \(1/x\) turns negative, \(e^{1/x}\) diminishes, drawing near to zero, exemplified by the left-hand limit.
Key characteristics of exponential functions include: - Rapid growth or decay: They respond swiftly to changes in the exponent. - Asymptotic behavior: As with this function, exponents going towards \(+\infty\) or \(-\infty\) make the function grow indefinitely or shrink towards zero. Understanding this nature helps in analyzing different scenarios of the function's limits.
- **Positive Exponent**: If \(1/x\) is positive, \(e^{1/x}\) escalates sharply, as we observed with the right-hand limit moving to \(+\infty\). - **Negative Exponent**: When \(1/x\) turns negative, \(e^{1/x}\) diminishes, drawing near to zero, exemplified by the left-hand limit.
Key characteristics of exponential functions include: - Rapid growth or decay: They respond swiftly to changes in the exponent. - Asymptotic behavior: As with this function, exponents going towards \(+\infty\) or \(-\infty\) make the function grow indefinitely or shrink towards zero. Understanding this nature helps in analyzing different scenarios of the function's limits.