/*! 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 55 Calculate the derivative of the ... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Calculate the derivative of the following functions. $$y=4 \log _{3}\left(x^{2}-1\right)$$

Short Answer

Expert verified
Answer: The derivative of the function is $$\frac{dy}{dx} = \frac{8x}{(x^2 - 1) \ln 3}$$.

Step by step solution

01

Rewrite using the natural logarithm

Recall that an arbitrary logarithm can be rewritten using the natural logarithm. The base change formula will be helpful here: $$y = 4 \log_{3}\left(x^2 - 1\right) = \frac{4}{\ln 3} \ln\left(x^2 - 1\right)$$
02

Differentiate using the chain rule

Now apply the chain rule, which states that the derivative of a composite function is the derivative of the outer function times the derivative of the inner function. So, we have to first differentiate the natural logarithm and then differentiate the quadratic function. The chain rule can be written as: $$\frac{dy}{dx} = \frac{d(\frac{4}{\ln 3} \ln (x^2 -1))}{dx} = \frac{4}{\ln 3} \cdot \frac{d\ln(x^2 - 1)}{dx}$$
03

Differentiate the natural logarithm function

Differentiate the natural logarithm function with the chain rule, and apply the power rule to the inner function: $$\frac{d\ln(x^2-1)}{dx} = \frac{1}{x^2 - 1} \cdot \frac{d(x^2 - 1)}{dx}$$
04

Differentiate the quadratic function

Now differentiate the inner quadratic function: $$\frac{d(x^2 - 1)}{dx} = 2x$$
05

Combine the results

Combine the results from Steps 2, 3, and 4: $$\frac{dy}{dx} = \frac{4}{\ln 3} \cdot \frac{1}{x^2 - 1} \cdot 2x$$
06

Simplify the derivative

Finally, simplify the expression by multiplying through: $$\frac{dy}{dx} = \frac{8x}{(x^2 - 1) \ln 3}$$ So, the derivative of the function is: $$\frac{dy}{dx} = \frac{8x}{(x^2 - 1) \ln 3}$$

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.

Chain Rule
Understanding the chain rule is crucial when differentiating composite functions. Picture it as a process of peeling an onion, layer by layer. For a composite function, where one function is nested within another, the chain rule states that you differentiate the outer function and multiply it by the derivative of the inner function.

For example, if you're faced with a function like \(\ln (x^2 - 1)\), the outer function is the logarithm and the inner function is \(x^2 - 1\). To differentiate this using the chain rule, you'd take the derivative of \(\ln u\) where \(u = x^2 - 1\), and multiply it by the derivative of \(u\) with respect to \(x\). This step is essential for succeeding in calculus, especially when dealing with complex expressions.
Natural Logarithm
The natural logarithm, denoted as \(\ln\), is a special logarithm with the base \(e\), where \(e\) is an irrational and transcendental number approximately equal to 2.71828. It emerges naturally in calculus because of its unique properties, particularly when dealing with growth processes and areas under hyperbola.

When you see a logarithmic function in an expression you're meant to differentiate, understanding that the derivative of \(\ln x\) with respect to \(x\) is \(1/x\) is pivotal. This knowledge simplifies the process significantly, positioning you to tackle a wide variety of calculus problems with confidence.
Base Change Formula
In calculus, the base change formula is a helpful tool that allows you to rewrite logarithms of any base in terms of natural logarithms. The formula is \(\log_a(b) = \frac{\ln(b)}{\ln(a)}\), where \(a\) is the base of the logarithm and \(b\) is the value being logged.

When faced with different bases, the base change formula becomes invaluable. For instance, in our exercise, by using this formula, we convert \(\log_3(x^2 - 1)\) to a form that involves the natural logarithm, making it much more manageable to take the derivative using rules that are typically easier to apply to natural logarithms.
Power Rule
The power rule is a basic differentiation rule used to handle functions of the form \(x^n\). It states that if you have a power function, its derivative is \(n * x^{n - 1}\). So, if you need to differentiate \(x^2\), the power rule tells you to bring down the exponent as a coefficient and subtract one from the exponent.

In the given exercise, the power rule enables you to take the derivative of the inner function \(x^2 - 1\), producing \(2x\). It’s a straightforward yet powerful tool at your disposal, especially when dealing with polynomial functions where each term can be differentiated independently.
Composite Function Differentiation
Differentiating composite functions requires a skillful application of the chain rule. A composite function is essentially a function inside another function, and when differentiating, you work from the outside in. It requires patience and precision to ensure each layer is addressed appropriately.

As outlined in the exercise, you first differentiate the outer function, which involves the logarithm, and then you tackle the derivative of the inner quadratic function. The process showcases how the chain rule is effectively utilized to unpack and solve derivatives of functions that are embedded within each other. Mastering this concept is fundamental for in-depth calculus problem-solving.

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

Orthogonal trajectories Two curves are orthogonal to each other if their tangent lines are perpendicular at each point of intersection (recall that two lines are perpendicular to each other if their slopes are negative reciprocals). A family of curves forms orthogonal trajectories with another family of curves if each curve in one family is orthogonal to each curve in the other family. For example, the parabolas \(y=c x^{2}\) form orthogonal trajectories with the family of ellipses \(x^{2}+2 y^{2}=k,\) where \(c\) and \(k\) are constants (see figure). Find \(d y / d x\) for each equation of the following pairs. Use the derivatives to explain why the families of curves form orthogonal trajectories. \(y=m x ; x^{2}+y^{2}=a^{2},\) where \(m\) and \(a\) are constants

A lighthouse stands 500 m off a straight shore and the focused beam of its light revolves four times each minute. As shown in the figure, \(P\) is the point on shore closest to the lighthouse and \(Q\) is a point on the shore 200 m from \(P\). What is the speed of the beam along the shore when it strikes the point \(Q ?\) Describe how the speed of the beam along the shore varies with the distance between \(P\) and \(Q\). Neglect the height of the lighthouse.

Calculating limits exactly Use the definition of the derivative to evaluate the following limits. $$\lim _{x \rightarrow 2} \frac{5^{x}-25}{x-2}$$

a. Determine an equation of the tangent line and normal line at the given point \(\left(x_{0}, y_{0}\right)\) on the following curves. b. Graph the tangent and normal lines on the given graph. \(\left(x^{2}+y^{2}-2 x\right)^{2}=2\left(x^{2}+y^{2}\right)\) \(\left(x_{0}, y_{0}\right)=(2,2)\) (limaçon of Pascal)

General logarithmic and exponential derivatives Compute the following derivatives. Use logarithmic differentiation where appropriate. $$\frac{d}{d x}\left(x^{\cos x}\right)$$

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.