Greens theorem boundary of a rectangle

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Homework Help Overview

The discussion revolves around applying Green's theorem to evaluate a line integral over a rectangular boundary defined by the curves \(x=1\), \(x=3\), \(y=2\), and \(y=3\). Participants are examining the integral of the vector field given by the expressions \(xy^2 - y^3\) and \(-5x^2 + y^3\).

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the calculation of partial derivatives and the application of Green's theorem. There are attempts to verify the correctness of the derivatives involved in the integral. Questions arise regarding the integration process and whether direct evaluation along the path has been performed as a verification step.

Discussion Status

Some participants have pointed out potential miscalculations in the derivatives, prompting a reevaluation of the initial setup. There is an ongoing exploration of different methods to approach the problem, including direct integration along the path.

Contextual Notes

There appears to be some confusion regarding the calculation of derivatives, which may affect the overall evaluation of the integral. The original poster's setup and the assumptions made about the vector field are also under scrutiny.

jonroberts74
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Homework Statement



##\mathscr{C}: x=1,x=3,y=2,y=3##

##\int_\mathscr{C} (xy^2-y^3)dx+(-5x^2+y^3)dy##

Homework Equations





The Attempt at a Solution



##\frac{\partial Q}{\partial x} = -10x^2 \,\,; \frac{\partial P}{\partial y} = 2xy-3y^2##

##\int\int_\mathscr{C} \frac{\partial Q}{\partial x} - \frac{\partial P}{\partial y} dA = \displaystyle \int_{2}^{3}\int_{1}^{3} (-10x^2-2xy+3y^2)dxdy = -\frac{206}{3}##
 
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You miscalculated dQ/dx.
 
vela said:
You miscalculated dQ/dx.

oh haha, -10x not ##-10x^2## thanks
 
Of course, it is easy to do the integration around the path directly as a check. Have you done that?
 

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