Chapter 13: Problem 65
Find the value of \(\partial z / \partial x\) at the point (1,1,1) if the equation $$ x y+z^{3} x-2 y z=0 $$ defines \(z\) as a function of the two independent variables \(x\) and \(y\) and the partial derivative exists.
Short Answer
Expert verified
\(\partial z / \partial x = -2\) at the point (1, 1, 1).
Step by step solution
01
Implicit Differentiation Setup
Given the equation \(x y + z^3 x - 2 y z = 0\), we are to find \(\frac{\partial z}{\partial x}\) using implicit differentiation. Treat \(z\) as a function of \(x\) and \(y\), then differentiate both sides of the equation with respect to \(x\) while treating \(y\) as a constant.
02
Differentiate Each Term
Differentiate each term with respect to \(x\). The first term \(x y\) differentiates to \(y\). The second term \(z^3 x\), using the product rule, differentiates to \(z^3 + 3z^2 x \frac{\partial z}{\partial x}\). The third term \(-2yz\), applying the product rule, differentiates to \(-2y \frac{\partial z}{\partial x}\).
03
Combine and Simplify
Combine the differentiated terms: \[ y + z^3 + 3z^2 x \frac{\partial z}{\partial x} - 2y \frac{\partial z}{\partial x} = 0. \]Rearrange the equation to solve for \(\frac{\partial z}{\partial x}\):\[ 3z^2 x \frac{\partial z}{\partial x} - 2y \frac{\partial z}{\partial x} = - (y + z^3). \]
04
Factor and Solve for \(\partial z/\partial x\)
Factor \(\frac{\partial z}{\partial x}\) out:\[ \frac{\partial z}{\partial x} (3z^2 x - 2y) = - (y + z^3). \]Solve for \(\frac{\partial z}{\partial x}\):\[ \frac{\partial z}{\partial x} = -\frac{y + z^3}{3z^2 x - 2y}. \]
05
Evaluate at the Given Point
Substitute the point \((1,1,1)\) into the expression for \(\frac{\partial z}{\partial x}\):\[ \frac{\partial z}{\partial x} = -\frac{1 + 1^3}{3(1)^2(1) - 2(1)} = -\frac{2}{3 - 2} = -2. \]
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.
Implicit Differentiation
In mathematics, implicit differentiation is a method used when dealing with equations where one variable is not explicitly expressed as a function of another. Here, variables are intertwined, making it difficult to isolate one on one side of the equation.
To tackle this:
To tackle this:
- We differentiate each term with respect to the variable of interest.
- We treat the other variables as constants unless they are explicitly functions of the main variable.
- This method is particularly useful when dealing with relations involving multiple variables where direct differentiation is cumbersome.
Partial Derivatives
Partial derivatives are a core element of calculus involving functions of multiple variables. They measure how a function changes as one of the variables changes, with others held constant.
Here is how it works:
Here is how it works:
- The notation \( \frac{\partial f}{\partial x} \) denotes the partial derivative of a function \( f \) concerning \( x \), treating other variables like \( y \) as constants.
- Partial derivatives help describe surfaces and multidimensional shapes, giving insight into how those surfaces behave.
Multivariable Calculus
Multivariable calculus extends the ideas of calculus from single-variable functions to those involving several variables. It is foundational for disciplines that require modeling real-world phenomena involving more than one variable at a time.
Key aspects include:
Key aspects include:
- Functions that can depend on multiple inputs, e.g., \( f(x, y, z) \).
- Techniques like finding critical points using gradients, Jacobians, and Hessians.
- Applications across physics, engineering, economics, and more due to its ability to handle complex models.