/*! 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 16 Find \(d y / d x\) by implicit d... [FREE SOLUTION] | 91Ó°ÊÓ

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Find \(d y / d x\) by implicit differentiation. $$\tan (x-y)=\frac{y}{1+x^{2}}$$

Short Answer

Expert verified
\(\frac{dy}{dx} = \frac{\sec^2(x-y)\cdot(1+x^2)^2 + 2xy}{(1+x^2)\cdot\sec^2(x-y) + 1+x^2}\)

Step by step solution

01

Differentiate Both Sides

To differentiate both sides with respect to \(x\), apply implicit differentiation. On the left, differentiate \(\tan(x-y)\) using the chain rule which results in \(\sec^2(x-y)\cdot(1 - \frac{dy}{dx})\). On the right, differentiate \(\frac{y}{1+x^2}\) using the quotient rule resulting in \(\frac{(1+x^2)\cdot \frac{dy}{dx} - y\cdot 2x}{(1+x^2)^2}\).
02

Set Up the Equation

Equate the derivatives from both sides: \[\sec^2(x-y) \cdot (1 - \frac{dy}{dx}) = \frac{(1+x^2)\cdot \frac{dy}{dx} - y\cdot 2x}{(1+x^2)^2}.\] This represents the differentiated equation.
03

Separate \(\frac{dy}{dx}\) Terms

Rearrange the equation to gather all terms involving \(\frac{dy}{dx}\) to one side of the equation: \[ \sec^2(x-y) - \sec^2(x-y)\cdot\frac{dy}{dx} = \frac{dy}{dx}\cdot\frac{1+x^2}{(1+x^2)^2} - \frac{2xy}{(1+x^2)^2}. \]
04

Isolate \(\frac{dy}{dx}\)

Factor out \(\frac{dy}{dx}\) from the terms on the right-hand side and solve for it: \[\frac{dy}{dx}\left(\frac{1+x^2}{(1+x^2)^2} + \sec^2(x-y)\right) = \sec^2(x-y) + \frac{2xy}{(1+x^2)^2}.\] Then, \(\frac{dy}{dx}\) is isolated: \[\frac{dy}{dx} = \frac{\sec^2(x-y) + \frac{2xy}{(1+x^2)^2}}{\frac{1+x^2}{(1+x^2)^2} + \sec^2(x-y)}.\]
05

Simplify the Expression

Combine terms and simplify the expression for \(\frac{dy}{dx}\) as needed: \[\frac{dy}{dx} = \frac{\sec^2(x-y)\cdot(1+x^2)^2 + 2xy}{(1+x^2)\cdot\sec^2(x-y) + 1+x^2}.\] This is your final solution.

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Key Concepts

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

The Chain Rule
The chain rule is a fundamental tool in calculus used when differentiating composite functions. It simplifies the process of finding the derivative of functions within other functions. In essence, the chain rule helps you breakdown complex derivatives into manageable parts by applying differentiation to both the outer and inner functions.

Consider a function of the form \(f(g(x))\). To differentiate this, you would take the derivative of \(f\) with respect to \(g(x)\), written as \(f'(g(x))\), and then multiply it by the derivative of \(g(x)\) with respect to \(x\), noted as \(g'(x)\). This gives us \((f(g(x)))' = f'(g(x)) \cdot g'(x)\).
  • For example, differentiating \(\tan(x-y)\) involves recognizing \(x-y\) as the inner function and \(\tan\) as the outer function.
  • Using the chain rule here gives you \(\sec^2(x-y)\cdot(1 - \frac{dy}{dx})\), as you differentiate \(x-y\) as part of the chain process.
The Quotient Rule
The quotient rule comes into play when you need to differentiate a function formed by the division of two different functions. Understanding and applying this rule correctly is essential for working with rational functions and their derivatives.

When you have a function \(\frac{g(x)}{h(x)}\), the quotient rule states that the derivative of the function is given by:
  • \((\frac{g}{h})' = \frac{g'(x)h(x) - g(x)h'(x)}{(h(x))^2}\)
In the provided exercise, you apply the quotient rule to \(\frac{y}{1+x^2}\). By differentiating \(y\) and \(1+x^2\), you obtain:
  • Numerator: \((1+x^2) \cdot \frac{dy}{dx} - y \cdot 2x\)
  • Denominator: \((1+x^2)^2\)
This results in \(\frac{(1+x^2) \cdot \frac{dy}{dx} - y \cdot 2x}{(1+x^2)^2}\), which forms part of the equation to be solved.
Trigonometric Differentiation
Trigonometric differentiation deals with finding the derivatives of trigonometric functions. It's a critical skill, particularly in calculus problems like the given exercise, where trigonometric functions are present on one side of the equation.

For the function \(\tan(x-y)\), its derivative can be found using a trigonometric identity where the derivative of \(\tan(u)\) is \(\sec^2(u)\). Combined with the chain rule, it becomes:
  • \(\sec^2(x-y)\cdot(1 - \frac{dy}{dx})\)
This result is crucial for setting up the equation for implicit differentiation. You use your understanding of trigonometric derivatives to form equations, equating both trigonometric and rational derivatives from each side of the original problem.
Calculus Problem Solving
Solving calculus problems often involves a systematic approach. Key skills include applying rules like the chain and quotient rules, understanding trigonometric derivatives, and algebraic manipulation for simplification.

For the exercise provided, implicit differentiation is essential due to the presence of both \(x\) and \(y\) in the function \(\tan(x-y) = \frac{y}{1+x^2}\). Implicit differentiation allows you to find \(\frac{dy}{dx}\) by treating \(y\) as a function of \(x\) even though \(y\) isn't isolated from \(x\).
  • Start by differentiating each side of the equation with respect to \(x\).
  • Collect terms involving \(\frac{dy}{dx}\) to one side to isolate the derivative.
  • Factor out \(\frac{dy}{dx}\), and then finally solve for it.
This kind of problem solving highlights the use of various differentiation rules in tandem, ensuring comprehensive understanding and application in calculus.

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Most popular questions from this chapter

Some of the highest tides in the world occur in the Bay of Fundy on the Atlantic Coast of Canada. At Hopewell Cape the water depth at low tide is about 2.0 \(\mathrm{m}\) and at high tide it is about 12.0 \(\mathrm{m} .\) The natural period of oscillation is a little more than 12 hours and on June \(30,2009,\) high tide occurred at \(6 : 45\) AM. This helps explain the following model for the water depth \(D\) (in meters) as a function of the time \(t\) (in hours after midnight) on that day: $$D(t)=7+5 \cos [0.503(t-6.75)]$$ How fast was the tide rising (or falling at the following times? $$\begin{array}{ll}{\text { (a) } 3 : 00 \mathrm{AM}} & {\text { (b) } 6 : 00 \mathrm{AM}} \\ {\text { (c) } 9 : 00 \mathrm{AM}} & {\text { (d) Noon }}\end{array}$$

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