((40X-X^2)^0.5)X^2的原函数是多少,

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((40X-X^2)^0.5)X^2的原函数是多少,

((40X-X^2)^0.5)X^2的原函数是多少,
((40X-X^2)^0.5)X^2的原函数是多少,

((40X-X^2)^0.5)X^2的原函数是多少,
x-20 = 20cosA ;
dx = -20sinA dA;
Int{(x^2)*sqrt(40x-x^2)dx}
=Int{(x^2)*sqrt(400-400+40x-x^2)}dx
=Int{(x^2)*sqrt(400-(x-20)^2)}dx
=Int{(20+20cosA)^2 * 20sinA *(-20sinA)}dA
=20^4 * int{ (cosA)^4 + 2(cosA)^3 + 2cosA + 1 }dA
剩下的自己算吧.