Chapter 1: Problem 41
Use a calculator to graph the function and estimate the value of the limit, then use L'H么pital's rule to find the limit directly. $$ \lim _{x \rightarrow 0} \frac{e^{x}-1}{x} $$
Short Answer
Expert verified
The limit is 1.
Step by step solution
01
Graph the Function
First, plot the function \( f(x) = \frac{e^{x}-1}{x} \) using a graphing calculator or software. Observe the behavior of the curve as \( x \) approaches 0. This will give you a visual estimation of the limit.
02
Estimate the Limit from the Graph
From the graph, as \( x \) approaches 0, the function appears to approach the value 1. This suggests that the limit might be 1.
03
Apply L'H么pital's Rule
The limit \( \lim_{x \to 0} \frac{e^x - 1}{x} \) is in the indeterminate form \( \frac{0}{0} \). According to L'H么pital's Rule, if a limit is in the form \( \frac{0}{0} \) or \( \frac{\infty}{\infty} \), it can be evaluated as: \[ \lim_{x \to c} \frac{f(x)}{g(x)} = \lim_{x \to c} \frac{f'(x)}{g'(x)} \]provided that the limit on the right exists. Here, \( f(x) = e^x - 1 \) and \( g(x) = x \).
04
Compute the Derivatives
Compute the derivatives of the numerator and the denominator. The derivative of \( f(x) = e^x - 1 \) is \( f'(x) = e^x \). The derivative of \( g(x) = x \) is \( g'(x) = 1 \).
05
Calculate the Limit Using L'H么pital's Rule
Substitute the derivatives back into the L'H么pital's Rule formula:\[ \lim_{x \to 0} \frac{e^x - 1}{x} = \lim_{x \to 0} \frac{e^x}{1} = \lim_{x \to 0} e^x \]As \( x \rightarrow 0 \), \( e^x \rightarrow e^0 = 1 \).
06
Confirm the Limit from Step 5
From both the graphical estimation and L'H么pital's Rule calculation, the limit is confirmed to be 1 as \( x \rightarrow 0 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Limits
The concept of limits is fundamental in calculus. A limit approaches a particular value as the input gets closer to a specific point. In this exercise, we're trying to find the limit of \( \frac{e^x - 1}{x} \) as \( x \) approaches zero.
Why are limits important? They help us understand the behavior of functions at points where they may not be directly defined. For example, if plugging in zero directly resulted in division by zero, limits allow us to find values the function approaches.
In practice, we can estimate limits by observing graphs. As described in the solution, plotting the graph of \( f(x) = \frac{e^x - 1}{x} \), you can visually see how the function behaves near the point of interest, in this case, as \( x \) approaches 0. This estimation can then be mathematically confirmed using more precise tools like L'H么pital's Rule.
Why are limits important? They help us understand the behavior of functions at points where they may not be directly defined. For example, if plugging in zero directly resulted in division by zero, limits allow us to find values the function approaches.
In practice, we can estimate limits by observing graphs. As described in the solution, plotting the graph of \( f(x) = \frac{e^x - 1}{x} \), you can visually see how the function behaves near the point of interest, in this case, as \( x \) approaches 0. This estimation can then be mathematically confirmed using more precise tools like L'H么pital's Rule.
Derivatives
Derivatives are another core concept in calculus and are essential for applying L'H么pital's Rule. A derivative represents the rate of change of a function concerning its variable.
To apply L'H么pital's Rule, we need to find the derivatives of the numerator and denominator of the function in this indeterminate form. In the solution above:
To apply L'H么pital's Rule, we need to find the derivatives of the numerator and denominator of the function in this indeterminate form. In the solution above:
- The derivative of the numerator \( f(x) = e^x - 1 \) is \( f'(x) = e^x \).
- The derivative of the denominator \( g(x) = x \) is \( g'(x) = 1 \).
Indeterminate Forms
Indeterminate forms play a significant role when calculating limits. They are expressions like \( \frac{0}{0} \) or \( \frac{\infty}{\infty} \) that do not initially provide a clear numerical result.
In our exercise, the limit \( \lim_{x \to 0} \frac{e^x - 1}{x} \) initially yields an indeterminate form \( \frac{0}{0} \). This indicates that the direct evaluation of the limit does not provide a straightforward answer.
L'H么pital's Rule is a technique designed to resolve these indeterminate forms by substituting the problematic form with one that can be evaluated simply by re-differentiating the numerator and denominator. Once applied, it transforms the problem into calculating \( \lim_{x \to 0} e^x \), which is clearly 1, resolving the indeterminacy and providing the exact limit value.
In our exercise, the limit \( \lim_{x \to 0} \frac{e^x - 1}{x} \) initially yields an indeterminate form \( \frac{0}{0} \). This indicates that the direct evaluation of the limit does not provide a straightforward answer.
L'H么pital's Rule is a technique designed to resolve these indeterminate forms by substituting the problematic form with one that can be evaluated simply by re-differentiating the numerator and denominator. Once applied, it transforms the problem into calculating \( \lim_{x \to 0} e^x \), which is clearly 1, resolving the indeterminacy and providing the exact limit value.