Chapter 3: Problem 7
Suppose that \(x\) and \(y\) are related by the given equation and use implicit differentiation to determine \(\frac{d y}{d x}\). $$2 x^{3}+y=2 y^{3}+x$$
Short Answer
Expert verified
\( \frac{dy}{dx} = \frac{6x^2 - 1}{6y^2 - 1} \)
Step by step solution
01
Differentiate Both Sides with Respect to x
Start by differentiating the equation implicitly with respect to x. Equation: \[ 2x^3 + y = 2y^3 + x \]Differentiating both sides results in: \[ \frac{d}{dx}(2x^3 + y) = \frac{d}{dx}(2y^3 + x) \]
02
Apply Chain Rule
When differentiating implicitly, apply the chain rule to terms involving y.For the left side: \[ \frac{d}{dx}(2x^3) + \frac{d}{dx}(y) = 6x^2 + \frac{dy}{dx} \]For the right side: \[ \frac{d}{dx}(2y^3) + \frac{d}{dx}(x) = 6y^2 \frac{dy}{dx} + 1 \]
03
Combine Results
Combine the results of the differentiations into a single equation.\[ 6x^2 + \frac{dy}{dx} = 6y^2 \frac{dy}{dx} + 1 \]
04
Solve for \( \frac{dy}{dx} \)
Isolate \( \frac{dy}{dx} \) on one side of the equation.First, move all terms involving \( \frac{dy}{dx} \) to one side:\[ 6x^2 + \frac{dy}{dx} - 6y^2 \frac{dy}{dx} = 1 \]Combine like terms:\[ 6x^2 = 1 - \frac{dy}{dx} + 6y^2 \frac{dy}{dx} \]Factor out \( \frac{dy}{dx} \):\[ 6x^2 = 1 + \frac{dy}{dx}(6y^2 - 1) \]Finally, solve for \( \frac{dy}{dx} \):\[ \frac{dy}{dx} = \frac{6x^2 - 1}{6y^2 - 1} \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Calculus
Calculus is a powerful branch of mathematics that deals with rates of change and the accumulation of quantities. It’s divided into two main parts: differentiation and integration. In this exercise, we are focusing on differentiation. Differentiation involves finding the rate at which one quantity changes with respect to another. For instance, how a function changes as its input changes. Implicit differentiation is particularly useful when the relationship between the variables is not explicitly given in the form of one variable as a function of the other. Instead, the variables are intertwined in an equation. Understanding these concepts will help you tackle problems like finding the derivative of a function implicitly.
The Chain Rule
The chain rule is a fundamental theorem in calculus used when differentiating composite functions. This rule helps to find the derivative of a function based on the derivatives of its inner functions. When a function is nested within another function, the chain rule is applied.
- Let’s say we have a function y = g(f(x)). To differentiate it, we use the chain rule:
\(\frac{dy}{dx} = \frac{dy}{df} \times \frac{df}{dx}\). - In simpler terms, it means 'the derivative of the outer function times the derivative of the inner function'.
- In implicit differentiation, this rule helps us handle the differentiation of functions involving y (where y is dependent on x) inside our equation.
For example, in the given solution, when differentiating terms involving y like \( 2y^3 \), we apply the chain rule: \(\frac{d}{dx}(2y^3) = 6y^2 \frac{dy}{dx}\).
What is a Derivative?
A derivative represents the rate of change of a function with respect to a variable. It's a measure of how a function changes as its input changes. In simple terms, it answers the question: 'how fast is something changing?'.
- This is written mathematically as \( \frac{dy}{dx} \) where 'y' is the dependent variable, and 'x' is the independent variable.
- In the context of our problem, \( \frac{dy}{dx}\) is what we are trying to find. This indicates how y changes with respect to x.
- One important method in finding derivatives, especially for complicated equations, involves implicit differentiation.
Implicit differentiation is used here because the variables x and y are not separated, as shown in the example: \(2 x^{3}+y = 2 y^{3}+x \). Differentiating directly term-by-term with respect to x, we can find how y changes.