/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 51 Make a conjecture about the limi... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Make a conjecture about the limit by graphing the function involved with a graphing utility; then check your conjecture using L'Hôpital's rule. $$ \lim _{x \rightarrow 0^{+}}(\sin x)^{3 / \ln x} $$

Short Answer

Expert verified
The limit is \(e^{-3}\).

Step by step solution

01

Graph the Function

To begin solving the limit problem, graph the function \((\sin x)^{3 / \ln x}\) using a graphing utility. Focus on values of \(x\) approaching 0 from the positive side of the x-axis. As \(x\) gets closer to 0, observe how the function behaves to make an initial conjecture of the limit.
02

Convert to Exponential Form

Rewrite the limit in a form that is easier to evaluate using L'Hôpital's rule:\[\lim_{x \to 0^+} (\sin x)^{3 / \ln x} = \lim_{x \to 0^+} e^{\frac{3 \ln(\sin x)}{\ln x}}\]This transformation simplifies the expression and allows us to tackle the indeterminate form \(\frac{0}{0}\) as \(x\) approaches 0.
03

Apply L'Hôpital's Rule

Evaluate the limit of the exponent by using L'Hôpital's rule:\[\lim_{x \to 0^+} \left( \frac{3 \ln(\sin x)}{\ln x} \right)\]Take derivatives of the numerator and denominator:- Derivative of the numerator \(3\ln(\sin x)\) with respect to \(x\): \(\frac{3\cos x}{\sin x}\)- Derivative of the denominator \(\ln x\) with respect to \(x\): \(\frac{1}{x}\)Apply L'Hôpital's Rule:\[\lim_{x \to 0^+} \frac{3 \cos x / \sin x}{1/x} = \lim_{x \to 0^+} 3x \cot x\]
04

Simplify to Find the Limit

Evaluate the simplified form \(3x\cot x\) as \(x\) approaches 0:\[\lim_{x \to 0^+} 3x \cot x = \lim_{x \to 0^+} \frac{3x \cos x}{\sin x} = 3 \times \lim_{x \to 0^+} \frac{x \cos x}{\sin x}\]Since \(\cot x\) approaches \(\frac{1}{x}\) as \(x\) approaches 0 from the right, the limit is 3. Thus,\[\lim_{x \to 0^+} \left( \frac{3 \ln(\sin x)}{\ln x} \right) = -3\]Using this result in the exponential form, the limit becomes \(e^{-3}\).
05

Conclude the Limit

Having evaluated the expression using L'Hôpital's rule:\[\lim_{x \to 0^+} e^{\left(\lim_{x \to 0^+} \frac{3 \ln(\sin x)}{\ln x}\right)} = e^{-3}\]This confirms our conjecture from graphing the function: the limit of \((\sin x)^{3 / \ln x}\) as \(x\) approaches 0 from the right is \(e^{-3}\).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Limit of a Function
In calculus, finding the limit of a function is one of the foundational concepts. It helps us understand the behavior of functions as they move closer to a specific point. The limit examines how a function behaves as the input, or variable, approaches a particular value. This doesn't necessarily mean the function reaches this value, but rather, it gets infinitely close.

In the problem \[ \lim _{x \rightarrow 0^{+}}(\sin x)^{3 / \ln x} \], we are interested in how this expression behaves as \(x\) gets very close to 0 from the right-hand side. Initially, by graphing the function, you can visually guess the limit, but for more precise answers, formal mathematical techniques like L'Hôpital's rule are often used.

By plotting the graph of \((\sin x)^{3 / \ln x}\), we begin with a conjecture based on visual cues. These conjectures guide our analytical evaluation to confirm the actual limit value, helping us connect visual understanding with analytical solutions. Learning how to determine limits analytically and graphically reinforces intuition and technical mastery in calculus.
Exponential Functions
Exponential functions are another important concept in mathematics, representing expressions where a constant base is raised to a variable exponent, like \(e^x\). In the context of the original problem, converting \((\sin x)^{3 / \ln x}\) into a form involving exponents is crucial.

One clever trick employed here is expressing the given power in terms of the natural exponent \(e\). By rewriting \(\lim_{x \to 0^+} (\sin x)^{3 / \ln x}\) as \(\lim_{x \to 0^+} e^{\frac{3 \ln(\sin x)}{\ln x}}\), the problem becomes more tractable.

Why is this beneficial? Because dealing with exponential functions often simplifies the evaluation process, especially when they involve indeterminate forms. This conversion allows us to take advantage of well-known limits related to exponential growth, helping simplify complex expressions into something more manageable. Recognizing when and how to switch to exponential form is a powerful skill in calculus, aiding in solving limits and other complex problems efficiently.
Indeterminate Forms
When evaluating limits, we often come across expressions that are not straightforward to solve right away, known as indeterminate forms. A common indeterminate form that arises is \(\frac{0}{0}\), which occurs when both the numerator and denominator approach zero as the variable approaches a certain value.

The expression \(\frac{3 \ln(\sin x)}{\ln x}\) results in an indeterminate form \(\frac{0}{0}\) as \(x\) approaches 0 from the positive side. This is where L'Hôpital's Rule shines, allowing us to differentiate the numerator and denominator separately to find the limit when direct substitution is impossible.

By applying L'Hôpital's Rule: - Compute the derivative of the numerator, \(3 \ln(\sin x)\), which gives \(\frac{3\cos x}{\sin x}\).
- Compute the derivative of the denominator, \(\ln x\), resulting in \(\frac{1}{x}\).

Reapplying L'Hôpital's Rule or simplifying the resulting expression can often resolve the indeterminate form, helping us to calculate the desired limit accurately. Recognizing indeterminate forms and using appropriate techniques like L'Hôpital's Rule is essential in bridging the gap between confusing, undefined expressions and meaningful, calculated limits.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

If the temperature \(T\) of a solid or liquid of volume \(V\) is changed by an amount \(\Delta T\), then the volume will change by the amount \(\Delta V=\beta V \Delta T\), where \(\beta\) is called the coefficient of volume expansion. For moderate changes in temperature \(\beta\) is taken as constant. Suppose that a tank truck loads 4000 gallons of ethyl alcohol at a temperature of \(35^{\circ} \mathrm{C}\) and delivers its load sometime later at a temperature of \(15^{\circ} \mathrm{C}\). Using \(\beta=7.5 \times 10^{-4} /{ }^{\circ} \mathrm{C}\) for ethyl alcohol, find the number of gallons delivered.

Find the differential \(d y\). (a) \(y=x \sqrt{1-x}\) (b) \(y=(1+x)^{-17}\)

The time required for one complete oscillation of a pendulum is called its period. If \(L\) is the length of the pendulum and the oscillation is small, then the period is given by \(P=2 \pi \sqrt{L / g}\), where \(g\) is the constant acceleration due to gravity. Use differentials to show that the percentage error in \(P\) is approximately half the percentage error in \(L\).

Suppose that the population of oxygen-dependent bacteria in a pond is modeled by the equation $$ P(t)=\frac{60}{5+7 e^{-t}} $$ where \(P(t)\) is the population (in billions) \(t\) days after an initial observation at time \(t=0\). (a) Use a graphing utility to graph the function \(P(t)\). (b) In words, explain what happens to the population over time. Check your conclusion by finding \(\lim _{t \rightarrow+\infty} P(t)\). (c) In words, what happens to the rate of population growth over time? Check your conclusion by graphing \(P^{\prime}(t)\).

Suppose that functions \(f\) and \(g\) are differentiable at \(x=a\) and that \(f(a)=g(a)=0 .\) If \(g^{\prime}(a) \neq 0\), show that $$ \lim _{x \rightarrow a} \frac{f(x)}{g(x)}=\frac{f^{\prime}(a)}{g^{\prime}(a)} $$ without using L'Hôpital's rule. [Hint: Divide the numerator and denominator of \(f(x) / g(x)\) by \(x-a\) and use the definitions for \(f^{\prime}(a)\) and \(\left.g^{\prime}(a) .\right]\)

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.