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CAF123
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Homework Statement
Evaluate [tex] \int_{R} \int \frac{xy^2}{(4x^2 + y^2)^2} dA [/tex] where R is the finite region enclosed by [itex] y = x^2\,\,\text{and}\,\, y = 2x [/itex]
The Attempt at a Solution
I think the easiest way to integrate is to first do it wrt x and then wrt y, i.e [tex] \int_{0}^{4} \int_{\frac{y}{2}}^{\sqrt{y}} \frac{xy^2}{(4x^2 +y^2)^2} dx dy, [/tex] where [tex] R = [(x,y) : \frac{y}{2} ≤ x ≤ \sqrt{y} , 0 ≤ y ≤ 4 ] [/tex]
Compute inner integral: Take [itex] y^2 [/itex] out of the integrand and let [itex] u = 4x^2 + y^2 [/itex]. Doing so and evaluating at [itex] x = \sqrt{y}, x = \frac{y}{2} [/itex] gives [tex] \frac{y^2}{8} [ -\frac{1}{4y + y^2} + \frac{1}{2y^2} ] [/tex]
Can somebody confirm this is correct up to here? When I do the subsequent integration wrt y, I get a negative answer for volume.
EDIT: It looks like this can be evaluated via polar coordinates which I will do once I have an answer using Cartesian.
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