∫1/(x^100+x)dx ∫1/(e^x+e^3x)dx
问题描述：
∫1/(x^100+x)dx ∫1/(e^x+e^3x)dx
答
1、∫1/(x^100+x)dx=∫1/x - x^98/(x^99+1) dx=∫1/x dx - ∫x^98 /(x^99+1) dx=lnx - 1/99 *∫ 1/(x^99+1) d(x^99)=lnx -1/99 *ln|x^99+1| +C C为常数2、∫1/(e^x+e^3x)dx=∫1/[e^x *(e^2x+1)] dx=∫ [1/e^x - e^x/...