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设二重积分的积分区域D是4≤x^2+y^2≤9则∫∫dxdy=
人气:118 ℃ 时间:2020-04-13 08:59:47
解答
4 ≤ x² + y² ≤ 9==> 4 ≤ r² ≤ 9==> 2 ≤ r ≤ 3∫∫D dxdy = D的面积 = π * 3² - π * 2² = 5π或极坐标的∫∫D dxdy = ∫(0,2π) dθ ∫(2,3) r dr= [ θ ]:(0,2π) * [ (1/2)r...
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