Let C be the closed, piecewise smooth curve formed by traveling in straight lines between the points (-2,1), (-2,-3), (1,-1) , (1,5), and back to (-2,1), in that order. Use Green's theorem to evaluate the integral:

Integral(C) (2xy) dx +(xy^2) dy

Respuesta :

The given points are the vertices of the quadrilateral

[tex]Q=\left\{(x,y)\mid-2\le x\le1,\dfrac{2x-5}3\le y\le\dfrac{4x+11}3\right\}[/tex]

By Green's theorem, the line integral is

[tex]\displaystyle\int_C2xy\,\mathrm dx+xy^2\,\mathrm dy=\iint_Q\frac{\partial(xy^2)}{\partial x}-\frac{\partial(2xy)}{\partial y}\,\mathrm dA[/tex]

[tex]=\displaystyle\int_{-2}^1\int_{(2x-5)/3}^{(4x+11)/3}y^2-2x\,\mathrm dy\,\mathrm dx=\boxed{61}[/tex]

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