/*! 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 53 Finding a Derivative of a Trigon... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Finding a Derivative of a Trigonometric Function. In Exercises \(39-54,\) find the derivative of the trigonometric function. $$ y=2 x \sin x+x^{2} \cos x $$

Short Answer

Expert verified
The derivative of the function \(y = 2x\sin{x} + x^{2}\cos{x}\) is \(y' = 2\sin{x} + 4x\cos{x} - x^2\sin{x}\)

Step by step solution

01

Apply the Product Rule on the First Term

Apply the product rule on \(2x\sin{x}\). The product rule states that the derivative of \(u(x)v(x)\) is \(u'(x)v(x) + u(x)v'(x)\). Let \(u(x) = 2x\) and \(v(x) = \sin{x}\). Thus, the derivative of \(2x\sin{x}\) is \((2)(\sin{x}) + (2x)(\cos{x})\).
02

Apply the Product Rule on the Second Term

Similar to step 1, apply the product rule on \(x^{2}\cos{x}\). Let \(u(x) = x^{2}\) and \(v(x) = \cos{x}\). So, the derivative of \(x^{2}\cos{x}\) is \((2x)(\cos{x}) - (x^{2})(\sin{x})\).
03

Combine the Results

The derivative of \(y = 2x\sin{x} + x^{2}\cos{x}\) is simply the derivatives of the two terms added together. Therefore, \(y' = (2)(\sin{x}) + (2x)(\cos{x}) + (2x)(\cos{x}) - (x^{2})(\sin{x})\).

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.

Product Rule
When differentiating functions in calculus, especially when these functions are products of two or more functions, the product rule is a vital tool.

The product rule states: Given two differentiable functions, say, u(x) and v(x), the derivative of their product u(x)v(x) is given by u'(x)v(x) + u(x)v'(x). This can be thought of as differentiating each function individually and then summing the two products together.

For example, applying the product rule to the term 2xsin(x), we designate u(x) = 2x and v(x) = sin(x). After computing derivatives individually for u'(x) and v'(x) and applying the product rule, the resulting derivative of the term is (2)sin(x) + (2x)cos(x).

Thus, mastering the product rule is crucial for effectively dealing with multiplication of functions in differentiation.
Calculus
Calculus is a branch of mathematics that studies continuous change, and it's divided primarily into two areas: differential calculus and integral calculus.

Differential calculus concerns itself with the concept of a derivative, which represents an instantaneous rate of change, or in a more graphical sense, the slope of the tangent to a curve at any point. On the other hand, integral calculus deals with the accumulation of quantities, such as areas under curves.

The problem we are addressing involves differential calculus. Finding the derivative of a function like y = 2xsin(x) + x2cos(x) requires understanding and applying derivative rules, including the product rule, to manage the combination of polynomial and trigonometric functions.
Trigonometry
Trigonometry is a study of triangles, particularly right triangles, and the relationships between their angles and sides. It also extends to the circular functions like sine, cosine, and tangent, which are fundamental in describing periodic phenomena.

In the context of calculus, trigonometry is essential because trigonometric functions such as sin(x) and cos(x) appear frequently in various applications. Differentiation of trigonometric functions follows specific rules, such as the derivative of sin(x) being cos(x), and the derivative of cos(x) being -sin(x).

Understanding how to differentiate these functions is crucial when they are part of a larger expression being differentiated, as seen in our exercise involving the product rule.
Differentiation
Differentiation is the process of determining the derivative of a function. It's one of the core operations in calculus and is used to study the way functions change.

The derivative itself is a concept that comes from the notion of rate of change and slope. In simple terms, finding a derivative gives you the slope of a curve at any given point. This is immensely useful in various disciplines such as physics, engineering, and economics, where understanding how one variable changes in relation to another is vital.

For trigonometric functions, differentiation rules help us find these rates of change. For instance, in our exercise, we use differentiation to find the slope of the tangent line to the curve at any point for the function y = 2xsin(x) + x2cos(x), allowing us to understand how y changes as x changes.

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

True or False? In Exercises \(93-96\) , determine whether the statement is true or false. If it is false, explain why or give an example that shows it is false. If a function has derivatives from both the right and the left at a point, then it is differentiable at that point.

Area The length of a rectangle is given by \(6 t+5\) and its height is \(\sqrt{t},\) where \(t\) is time in seconds and the dimensions are in centimeters. Find the rate of change of the area with respect to time.

True or False? In Exercises \(125-128\) , determine whether the statement is true or false. If it is false, explain why or give an example that shows it is false. If \(y\) is a differentiable function of \(u,\) and \(u\) is a differentiable function of \(x,\) then \(y\) is a differentiable function of \(x .\)

A boat is pulled into a dock by means of a winch 12 feet above the deck of the boat (see figure). (a) The winch pulls in rope at a rate of 4 feet per second. Determine the speed of the boat when there is 13 feet of rope out. What happens to the speed of the boat as it gets closer to the dock? (b) Suppose the boat is moving at a constant rate of 4 feet per second. Determine the speed at which the winch pulls in rope when there is a total of 13 feet of rope out. What happens to the speed at which the winch pulls in rope as the boat gets closer to the dock?

Finding a Pattern In Exercises 123 and \(124,\) find the derivatives of the function \(f\) for \(n=1,2,3,\) and \(4 .\) Use the results to write a general rule for \(f^{\prime}(x)\) in terms of \(n .\) $$ f(x)=x^{n} \sin x $$

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.