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1/(sin^4xCos^4x)的不定积分

分子分母同除以 cos^4x

前面是sinx的4次方还是sin4x啊

=∫sin^4x(1-sin^2x)dsinx上面就是将sinx作为自变量,你可设sinx=u则:=fu^4(1-u^2)du=f[u^4-u^6]du 公式:(u^n)'=(n-1)^(n-1) ; fu^ndu=1/(n+1) *u^(n+1)+c=fu^4du-fu^6du=1/5u^5-1/7u^7+c再将u=sinx代入=1/5sin^5x-1/7sin^7x+c

=-∫csc²xdcotx =-∫cot²x+1dcotx =-cot³x/3-cotx+C

-[cos(2x)^3]/3+cos(2x)/2+C

sin^2x(1-sin^2x)^2dx=sin^2x(1-2sin^2x+sin^4x)dx =sin^2xdx-2sin^4xdx+sin^6xdx 再用sin^nx公式,好像是 =(1/2)(pi/2)-2(3/4)(1/2)(pi/2)+(5/6)(3/4)(1/2)(pi/2)

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