级数∑（100/n(n+1)-100/3^)的和s

利用高斯判别设a_n=1/3^(n^(1/2))
a_n/a_(n+1)=3^((n+1)^(1/2)-n^(1/2))=e^(((n+1)^(1/2)-n^(1/2))*ln3)
=1+ln3/((n+1)^(1/2)-n^(1/2))+o(n^(1/2))
>1+ln3/n
所