计算不定积分:$x^2lnxdx

有个符号我不会,就用$代替了 !!

第1个回答  2013-07-02
∫ x²lnx dx
= ∫ lnx d(1/3 * x³)
= (1/3)x³lnx - (1/3)∫ x³ d(lnx)、分部积分法
= (1/3)x³lnx - (1/3)∫ x³ * 1/x dx
= (1/3)x³lnx - (1/3)∫ x² dx
= (1/3)x³lnx - (1/3)(x³/3) + C
= (x³/9)(3lnx - 1) + C