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For each equation, use implicit differentiation to find \(d y / d x\). $$ \frac{1}{x}+\frac{1}{y}=2 $$

Short Answer

Expert verified
The derivative \( \frac{dy}{dx} \) is \( -\frac{y^2}{x^2} \).

Step by step solution

01

Differentiate both sides implicitly with respect to x

Start by differentiating each term with respect to \(x\). For the first term, differentiating \(\frac{1}{x}\) gives \(-\frac{1}{x^2}\). For the second term, by treating \(y\) as a function of \(x\), the derivative of \(\frac{1}{y}\) is \(-\frac{1}{y^2} \cdot \frac{dy}{dx}\) using the chain rule. The right side is a constant, so its derivative is zero.
02

Write the differentiated equation

After differentiating, the equation becomes:\[-\frac{1}{x^2} - \frac{1}{y^2} \cdot \frac{dy}{dx} = 0.\]
03

Solve for \(\frac{dy}{dx}\)

Reorganize the equation to isolate \(\frac{dy}{dx}\) on one side. Start by moving the \(-\frac{1}{x^2}\) term to the other side:\[-\frac{1}{y^2} \cdot \frac{dy}{dx} = \frac{1}{x^2}.\]Then multiply both sides by \(-y^2\) to solve for \(\frac{dy}{dx}\):\[\frac{dy}{dx} = -\frac{y^2}{x^2}.\]

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Key Concepts

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

Chain Rule
The chain rule is a fundamental concept in calculus, used when differentiating composite functions. Imagine you have a function within another function; the chain rule helps you find the derivative of these nested functions efficiently. In our example, we are differentiating terms where the variable is not isolated. Specifically, for the term \(\frac{1}{y}\), we see y as a function of x. The chain rule is then applied: first, differentiate the outer function, followed by the derivative of the inner function. In this case, we have to differentiate \(\frac{1}{y}\), which gives us \(-\frac{1}{y^2}\), and then multiply it by \(\frac{dy}{dx}\) because y itself is a function of x. This simplifies handling complexities in implicit differentiation.
Derivative
When we talk about derivatives, we're discussing the rate at which a function changes. It's like finding the 'slope' of a curve at a particular point. Derivatives are crucial in understanding how functions behave. In implicit differentiation, we take this idea a step further by finding derivatives of expressions where y is not isolated. Differentiating terms like \(\frac{1}{x}\) is straightforward, as it results in \(-\frac{1}{x^2}\). However, for \(\frac{1}{y}\), since y depends on x, the implicit differentiation technique—pairing with the chain rule—must be used to introduce \(\frac{dy}{dx}\). This shows the intricate relationship between x and y in the equation, underlining the concept of derivatives as tools to measure change.
Equation Solving
Once we've differentiated the equation implicitly, the challenge is to solve for \(\frac{dy}{dx}\). Solving equations in implicit differentiation involves rearranging terms to isolate \(\frac{dy}{dx}\). After differentiating, our equation is \(-\frac{1}{x^2} - \frac{1}{y^2} \cdot \frac{dy}{dx} = 0\). The next steps are akin to solving any equation:
  • First, move terms around to get \(\frac{dy}{dx}\) on one side (in this case, separate \(-\frac{1}{y^2} \cdot \frac{dy}{dx}\) and \(\frac{1}{x^2}\)).
  • Next, divide or multiply to isolate \(\frac{dy}{dx}\), leaving us with \(\frac{dy}{dx} = -\frac{y^2}{x^2}\).
This process of solving helps us understand how changes in x and y are interrelated, showcasing implicit differentiation's capacity to provide a solution even when variables are intertwined.
Calculus
Calculus is the branch of mathematics that studies how things change. It's divided broadly into differential and integral calculus. Implicit differentiation, the tool we're using here, is under differential calculus. This technique is especially useful when functions cannot be easily expressed explicitly as y = f(x). Implicit differentiation involves calculating the derivative of every term of the equation relative to x, even those including y. This method keeps calculus flexible and applicable to real-world scenarios, where relationships between variables are often not straightforward. Calculus aids in problem-solving by offering scalable solutions, from simple derivatives to complex interdependent equations, illustrating its power and utility.

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Most popular questions from this chapter

Find the equation of the tangent line to the curve at the given point using implicit differentiation. Cardioid \(\left(x^{2}+y^{2}-y\right)^{2}=x^{2}+y^{2} \quad\) at \(\quad(-1,0)\)

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