Line integrals, gradient fields

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Homework Help Overview

The discussion revolves around a problem involving line integrals and gradient fields, specifically focusing on finding a potential function given its gradient. The original poster presents a gradient vector field and seeks to determine the potential function at a specific point.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the relationship between the gradient and potential functions, with one participant questioning whether they are looking for a potential. Another suggests solving differential equations to find the potential function, indicating a method of integration and the use of constants.

Discussion Status

The discussion includes attempts to derive the potential function from the gradient, with some participants providing steps and reasoning. There is an acknowledgment of the original poster's confusion regarding the problem setup, and guidance is offered on how to approach finding the potential function.

Contextual Notes

Participants note that the original poster's textbook lacks examples similar to the problem, which may contribute to the confusion regarding the approach to take. The discussion also reflects on the implications of the initial condition provided in the problem.

jonroberts74
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Homework Statement



##\nabla{F} = <2xyze^{x^2},ze^{x^2},ye^{x^2}##
if f(0,0,0) = 5 find f(1,1,2)

Homework Equations


The Attempt at a Solution



my book doesn't have a good example of a problem like this, am I looking for a potential?

##<\frac{\partial}{\partial x},\frac{\partial}{\partial y},\frac{\partial}{\partial z} >= <2xyze^{x^2},ze^{x^2},ye^{x^2}>##
 
Last edited:
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jonroberts74 said:
my book doesn't have a good example of a problem like this, am I looking for a potential?
Yes, solve the three differential equations to find F(x,y,z) up to a constant. The given condition sets this constant, from which you can find F(x,y,z) for all x,y,z.
 
jonroberts74 said:

Homework Statement



##\nabla{F} = <2xyze^{x^2},ze^{x^2},ye^{x^2}##
if f(0,0,0) = 5 find f(1,1,2)

Homework Equations


The Attempt at a Solution



my book doesn't have a good example of a problem like this, am I looking for a potential?

##<\frac{\partial}{\partial x},\frac{\partial}{\partial y},\frac{\partial}{\partial z} >= <2xyze^{x^2},ze^{x^2},ye^{x^2}>##
##\frac{\partial}{\partial x} = 2xyze^{x^2} \Rightarrow \int 2xyze^{x^2}dx = yze^{x^2} + h(y,z)##

##\frac{\partial}{\partial y} = ze^{x^2} = ze^{x^2} + h(y,z) \Rightarrow h_{y}(y,z) = 0##

##\frac{\partial}{\partial z} = ye^{x^2} = ye^{x^2}+h(z) \Rightarrow h_{z}(z) = h'(z)##

##h'(z) = 0 \Rightarrow h(z) = k## for a constant k, and because f(0,0,0) = 5 then

##f= yze^{x^2} + 5##

so ##f(1,1,2) = 1(2)e^1+5 = 2e+5##
 
Last edited:
jonroberts74 said:
##\frac{\partial}{\partial x} = 2xyze^{x^2} \Rightarrow \int 2xyze^{x^2}dx = yze^{x^2} + h(y,z)##

##\frac{\partial}{\partial y} = ze^{x^2} = ze^{x^2} + h(y,z) \Rightarrow h_{y}(y,z) = 0##

##\frac{\partial}{\partial z} = ye^{x^2} = ye^{x^2}+h(z) \Rightarrow h_{z}(z) = h'(z)##

##h'(z) = 0 \Rightarrow h(z) = k## for a constant k, and because f(0,0,0) = 5 then

##f= yze^{x^2} + 5##

so ##f(1,1,2) = 1(2)e^1+5 = 2e+5##

Correct!

ehild
 

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