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Evaluate the limit. If the limit is of an indeterminate form, indicate the form and use L'Hôpital's Rule to evaluate the limit. $$ \lim _{x \rightarrow 5} \frac{(x-1)^{0.5}-2}{x^{2}-25} $$

Short Answer

Expert verified
The limit is \(\frac{1}{40}\).

Step by step solution

01

Identify the Indeterminate Form

First, we substitute \(x = 5\) into the function to determine if it results in an indeterminate form. Substituting gives \((5-1)^{0.5} - 2 = 2 - 2 = 0\) for the numerator and \(5^2 - 25 = 25 - 25 = 0\) for the denominator. Thus, the expression is of the form \(\frac{0}{0}\), which is indeterminate.
02

Apply L'Hôpital's Rule

Since the limit is in the \(\frac{0}{0}\) form, we can apply L'Hôpital's Rule. According to this rule, we differentiate the numerator and denominator separately.
03

Differentiate the Numerator

The numerator is \((x-1)^{0.5} - 2\). The derivative of \((x-1)^{0.5}\) is \(\frac{1}{2}(x-1)^{-0.5}\). So, the derivative of the numerator is \(\frac{1}{2}(x-1)^{-0.5}\).
04

Differentiate the Denominator

The denominator is \(x^2 - 25\). The derivative of \(x^2\) is \(2x\) and the derivative of \(-25\) is \(0\). Thus, the derivative of the denominator is \(2x\).
05

Evaluate the Limit of the New Expression

Substitute \(x = 5\) into the expression obtained by applying L'Hôpital's Rule: \[\lim _{x \rightarrow 5} \frac{\frac{1}{2}(x-1)^{-0.5}}{2x}.\]At \(x=5\), this becomes \[\frac{\frac{1}{2}(5-1)^{-0.5}}{2\times5} = \frac{\frac{1}{2} \times \frac{1}{2}}{10} = \frac{\frac{1}{4}}{10} = \frac{1}{40}.\]
06

Conclusion

The original limit evaluates to \(\frac{1}{40}\) after using L'Hôpital's Rule.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Understanding Indeterminate Forms
Indeterminate forms are expressions in calculus that do not have a clear value or limit. When attempting to evaluate a limit, you might encounter expressions like \( \frac{0}{0} \) or \( \frac{\infty}{\infty} \). These are called indeterminate because simply substituting values gives a result that doesn't provide meaningful information about the behavior of the function.
Identifying indeterminate forms is crucial when applying L'Hôpital's Rule, which specifically addresses these cases. The exercise at hand is an excellent example: substituting \(x = 5\) into the function results in a \(\frac{0}{0}\) form. Recognizing such forms allows us to move to techniques like L'Hôpital's Rule, which helps find the true limit in these tricky situations.
The Process of Limit Evaluation
Limit evaluation is a fundamental concept in calculus used to understand the behavior of functions as they approach a specific point. In this exercise, our goal was to determine the limit of a complicated expression as \(x\) approaches 5.
A direct substitution of \(x = 5\) gave us an indeterminate form, \(\frac{0}{0}\). This is a signal that it’s time to delve deeper using calculus techniques such as L'Hôpital's Rule. Limit evaluation becomes an exploration of the true nature of functions, requiring a nuanced approach beyond simple arithmetic operations.
Differentiation Steps in Applying L'Hôpital's Rule
Differentiation is the process of finding the derivative of a function and is a powerful tool in calculus, especially when dealing with L'Hôpital's Rule. In the exercise, we start by differentiating the numerator \((x-1)^{0.5} - 2\) to get \(\frac{1}{2}(x-1)^{-0.5}\). This involves recognizing the power rule and chain rule for derivatives.
Next, we differentiate the denominator \(x^2 - 25\), which is a straightforward application of the power rule, resulting in \(2x\). Differentiation allows us to transform the original expression into a form that can provide a definite limit, by eliminating the indeterminate form.
Integrating Calculus Techniques
Calculus is the mathematical study of change, and integrating its techniques can help solve complex limit problems effectively. Applying L'Hôpital's Rule is a perfect example of leveraging differential calculus to find limits that are otherwise indeterminate.
This exercise showed us the practical use of L'Hôpital's Rule as it allowed for the reduction of an indeterminate form to a determinate one. By differentiating the numerator and denominator separately, we turned a difficult \(\frac{0}{0}\) situation into a solvable problem, yielding a final limit of \(\frac{1}{40}\). Such techniques highlight the elegance and utility of calculus in understanding and solving real-world mathematical problems.

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Most popular questions from this chapter

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