x^2/(1+x^2)^2的积分是多少,怎么算

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x^2/(1+x^2)^2的积分是多少,怎么算
x^2/(1+x^2)^2的积分是多少,怎么算

x^2/(1+x^2)^2的积分是多少,怎么算
∫ x^2/(1+x^2)^2 dx
= ∫ dx/(1+x^2) -∫ dx/(1+x^2)^2
=arctanx -∫ dx/(1+x^2)^2
let
x=tany
dx = (secy)^2 dy
∫ dx/(1+x^2)^2
=∫ (cosy)^2 dy
=(1/2)∫ (1+cos2y) dy
=(1/2)[ y+(1/2)sin(2y) ]
=(1/2)[ arctanx +( x/(1+x^2) ) ]
∫ x^2/(1+x^2)^2 dx
=arctanx -∫ dx/(1+x^2)^2
=arctanx -(1/2)[ arctanx +(x/(1+x^2)) ]
=(1/2)arctanx -(1/2)[x/(1+x^2)] + C

∫ x^2/(1+x^2)^2 dx
= ∫ dx/(1+x^2) -∫ dx/(1+x^2)^2
=arctanx -∫ dx/(1+x^2)^2
let
x=tany
dx = (secy)^2 dy
∫ dx/(1+x^2)^2
=∫ (cosy)^2 dy
=(1/2)∫ (1+cos2y) dy
=(1/2)...

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∫ x^2/(1+x^2)^2 dx
= ∫ dx/(1+x^2) -∫ dx/(1+x^2)^2
=arctanx -∫ dx/(1+x^2)^2
let
x=tany
dx = (secy)^2 dy
∫ dx/(1+x^2)^2
=∫ (cosy)^2 dy
=(1/2)∫ (1+cos2y) dy
=(1/2)[ y+(1/2)sin(2y) ]
=(1/2)[ arctanx +( x/(1+x^2) ) ]
∫ x^2/(1+x^2)^2 dx
=arctanx -∫ dx/(1+x^2)^2
=arctanx -(1/2)[ arctanx +(x/(1+x^2)) ]
=(1/2)arctanx -(1/2)[x/(1+x^2)] + C

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