那设Tn=S2n-Sn,Tn+1大于Tn咋么证明?
追答Tn=S2n-Sn
=(1+...1/2n)-(1+.....1/n)
=1/(n+1)+...1/2n
Tn+1=S2(n+1)-Sn+1
=(1+......1/(2n+2))-(1+......1/(n+1))
=1/(n+2)+.....1/(2n+2)
所以Tn+1-Tn
=[1/(n+2)+.....1/(2n+2)]-[1/(n+1)+...1/2n]
=1/(2n+1)+1/(2n+2)-1/(n+1)
=1/(2n+1)-1/(2n+2)
=1/(2n+1)(2n+2)
>0
所以Tn+1大于Tn