[求助] 级数

2楼: Originally posted by hank612 at 2016-05-26 10:05:57
设S0=0, 则
\sum_{n=1}^{\infty}(S_n-S_{n-1})e^{-S_nx}\leq \sum_{k=0}^{\infty} S_k \int_{S_k}^{S_{k+1}}\frac{e^{-xt}}{x}dt\leq \sum \int_{S_k}^{S_{k+1}}\frac{te^{-xt}}{x}dt\leq \frac{1}{x^3}...