X3/X2+1dx的定积分
问题描述：
X3/X2+1dx的定积分
答
∫ x³/(x² + 1) dx
= ∫ x(x² + 1 - 1)/(x² + 1) dx
= ∫ x dx - ∫ x/(x² + 1) dx
= x²/2 - (1/2)ln(1 + x²) + C
= (1/2)[x² - ln(1 + x²)] + C