积分 ∫x^3/(1-x^2)^(3/2)dx

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积分∫x^3/(1-x^2)^(3/2)dx积分∫x^3/(1-x^2)^(3/2)dx积分∫x^3/(1-x^2)^(3/2)dx答:∫[x³/(1-x²)^(3/2)]dx=∫

积分 ∫x^3/(1-x^2)^(3/2)dx
积分 ∫x^3/(1-x^2)^(3/2)dx

积分 ∫x^3/(1-x^2)^(3/2)dx







答:
∫[x³/(1-x²)^(3/2)]dx
=∫[x³/(1-x²)√(1-x²)]dx         设x=sint,-π/2<t<π/2
=∫(sin³t/cos³t)d(sint)
=∫(sin³t/cos²t)dt
=-∫(sin²t/cos²t)d(cost)
=∫[(cos²t-1)/cos²t]d(cost)
=cost+1/cost+C
=√(1-x²)+1/√(1-x²)+C
=(2-x²)/√(1-x²)+C