Chapter 27: Problem 16
Evaluate each limit (if it exists). Use L'Hospital's rule (if appropriate). $$\lim _{x \rightarrow 0} \frac{\tan ^{-1} x}{x}$$
Short Answer
Expert verified
The limit is 1.
Step by step solution
01
Identify the Indeterminate Form
First, let's check if the limit as \( x \to 0 \) gives us an indeterminate form. We have \( \lim_{x \to 0} \frac{\tan^{-1} x}{x} \). Evaluating directly, \( \tan^{-1}(0) = 0 \) and \( x = 0 \), resulting in \( \frac{0}{0} \), an indeterminate form. This qualifies for the use of L'Hospital's Rule.
02
Apply L'Hospital's Rule
L'Hospital's Rule states that if \( \lim_{x \to a} \frac{f(x)}{g(x)} = \frac{0}{0} \text{ or } \frac{\infty}{\infty} \), then\[ \lim_{x \to a} \frac{f(x)}{g(x)} = \lim_{x \to a} \frac{f'(x)}{g'(x)} \] Apply L'Hospital’s Rule:- \( f(x) = \tan^{-1} x \), so \( f'(x) = \frac{1}{1+x^2} \)- \( g(x) = x \), so \( g'(x) = 1 \)Thus:\[ \lim_{x \to 0} \frac{\tan^{-1} x}{x} = \lim_{x \to 0} \frac{\frac{1}{1+x^2}}{1} = \lim_{x \to 0} \frac{1}{1+x^2} \]
03
Evaluate the New Limit
Now, we need to evaluate \( \lim_{x \to 0} \frac{1}{1+x^2} \).Plugging in \( x = 0 \) directly:\[ \frac{1}{1+0^2} = \frac{1}{1} = 1 \] Thus, the limit evaluates to 1.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Indeterminate Forms
In calculus, an indeterminate form arises when a mathematical expression does not lead to a clear answer or result upon direct substitution. One of the most common scenarios is when evaluating limits involving fractions. The expression may become something like \( \frac{0}{0} \) or \( \frac{\infty}{\infty} \), which are both examples of indeterminate forms.
When you encounter an indeterminate form such as \( \frac{0}{0} \), it indicates that direct evaluation is not sufficient to find the limit, and further analysis is necessary. L'Hospital's Rule is a powerful tool in such situations, allowing us to differentiate the numerator and the denominator separately to find the limit. This helps to resolve the indeterminate form and obtain a meaningful result.
When you encounter an indeterminate form such as \( \frac{0}{0} \), it indicates that direct evaluation is not sufficient to find the limit, and further analysis is necessary. L'Hospital's Rule is a powerful tool in such situations, allowing us to differentiate the numerator and the denominator separately to find the limit. This helps to resolve the indeterminate form and obtain a meaningful result.
Calculus Limits
The concept of limits is a fundamental aspect of calculus. It allows us to understand the behavior of functions as they approach a certain point or value. Calculus limits deal with the study of the behavior of functions when the input values approach a particular number.
For instance, when evaluating the limit \( \lim_{x \to 0} \frac{\tan^{-1} x}{x} \), we are essentially watching how the function \( \frac{\tan^{-1} x}{x} \) behaves as \( x \) approaches 0. Rather than evaluating the function exactly at the point, we focus on the trend or the value the function approaches.
For instance, when evaluating the limit \( \lim_{x \to 0} \frac{\tan^{-1} x}{x} \), we are essentially watching how the function \( \frac{\tan^{-1} x}{x} \) behaves as \( x \) approaches 0. Rather than evaluating the function exactly at the point, we focus on the trend or the value the function approaches.
- Limits provide insight into continuity and differentiability of functions.
- They are the backbone of calculus principles like derivatives and integrals.
- L'Hospital's Rule utilizes limits to evaluate expressions that are initially indeterminate.
Arctan Function
The arctan function, also known as the inverse tangent function, is denoted as \( \tan^{-1} x \). It is the inverse operation of the tangent function, which returns the angle whose tangent is \( x \). The domain of the arctan function covers all real numbers, and its range is from \(-\frac{\pi}{2}\) to \(\frac{\pi}{2}\).
In the context of limits, understanding the behavior of the arctan function at specific values such as 0 is crucial. For example, \( \tan^{-1}(0) = 0 \), which indicates that the angle whose tangent is 0 is 0 radians.
In the context of limits, understanding the behavior of the arctan function at specific values such as 0 is crucial. For example, \( \tan^{-1}(0) = 0 \), which indicates that the angle whose tangent is 0 is 0 radians.
- The derivative of the arctan function is \( \frac{1}{1+x^2} \), useful when applying L'Hospital's Rule for evaluating limits.
- The smooth curve of the function provides meaningful interpretations in various applied mathematics contexts, like physics and engineering.