Chapter 2: Problem 5
Find dy/dx by implicit differentiation. } $$ x^{3}-2 y^{3}-y=x+2 $$
Short Answer
Expert verified
The derivative \(\frac{dy}{dx}\) of the given function is \(\frac{3x^2 - 1}{6y^2 + 1}\).
Step by step solution
01
Differentiate both sides of the equation with respect to x
We will apply the rules for differentiating powers, constants, and products, treating y as a function of x:
$$
\frac{d}{dx}(x^3) - \frac{d}{dx}(2y^3) - \frac{d}{dx}(y) = \frac{d}{dx}(x) + \frac{d}{dx}(2)
$$
02
Differentiate each term on both sides of the equation
Applying the rules for differentiation, remembering to use the chain rule for terms involving y:
$$
(3x^2) - (6y^2)\frac{dy}{dx} - \frac{dy}{dx} = 1 + 0
$$
03
Solve for dy/dx
First, simplify the equation:
$$
3x^2 - 6y^2\frac{dy}{dx} - \frac{dy}{dx} = 1
$$
Combine the terms containing dy/dx:
$$
3x^2 - 1 = (6y^2 + 1)\frac{dy}{dx}
$$
Now, solve for dy/dx by dividing both sides by (6y^2 + 1)
$$
\frac{dy}{dx} = \frac{3x^2 - 1}{6y^2 + 1}
$$
The derivative dy/dx is therefore:
$$
\frac{dy}{dx} = \frac{3x^2 - 1}{6y^2 + 1}
$$
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Derivatives
Derivatives are fundamental to calculus and describe how a function changes as its input changes. In simple terms, a derivative tells us the rate of change of one quantity with respect to another. In mathematics, it's often written as \( \frac{dy}{dx} \), which signifies the derivative of \( y \) with respect to \( x \).
- The derivative can be visualized as the slope of a tangent line to a curve at any given point.
- In real-world terms, it's akin to measuring speed, where you see how distance changes over time.
- Implicit differentiation is used when functions are not given in a specific form that is easy to differentiate.
Exploring the Chain Rule
The Chain Rule is a powerful tool in calculus used for differentiating composite functions. A composite function is a function made up of two or more functions, layered one over the other.
- In the context of implicit differentiation, we treat \( y \) as a function of \( x \), even if it isn't explicitly stated.
- The Chain Rule allows us to find the derivative of such functions, by taking the derivative of the outer function and multiplying it by the derivative of the inner function.
- In our equation \( x^3 - 2y^3 - y = x + 2 \), we use the chain rule to differentiate terms involving \( y \).
Differentiation Rules Simplified
Differentiation rules provide a blueprint for finding derivatives of various types of functions. They are guidelines which show how to differentiate common functions.
- The power rule states that the derivative of \( x^n \) is \( nx^{n-1} \).
- Constant rule helps us understand that the derivative of a constant is zero.
- Sum difference rules allow us to take the derivative of terms added or subtracted in a straightforward manner.
Solving Equations with Implicit Differentiation
After differentiating the implicit function, we solve the equation to find the derivative of \( y \) with respect to \( x \). This process involves rearranging terms and solving for \( \frac{dy}{dx} \).
- The aim is to isolate \( \frac{dy}{dx} \) on one side of the equation.
- Combine terms containing \( \frac{dy}{dx} \) to simplify and solve the equation.
- Finally, divide by the remaining coefficient to solve for \( \frac{dy}{dx} \).