u = √(x³-2), u² = x³-2, 2u du = 3x² dx
I = ∫ x² dx / √(x³-2) = ∫ (2/3) du
= (2/3) u + C
= (2/3) √(x³-2) + C
如果被积函数如你所给,分母是 x^2, ...... ,则是不可积的。
令x=2^(1/3)*(sect)^(2/3) dx=2^(1/3)*(2/3)*(sect)^(2/3)*tantdt
∫ [(x^3-2)^(1/2)]/x^2 dx
=∫ [2^(1/2)*tant]/[2^(2/3)*(sect)^(4/3)]*2^(1/3)*(2/3)*(sect)^(2/3)*tantdt
=2^(1/6)*(2/3)*∫ [(tant)^2]/[(sect)^(2/3)] dt
=2^(1/6)*(2/3)*∫ [(sint)^2]/[(cost)^(4/3)] dt
=