用数学归纳法证明Sn=1/(n+1)+1/(n+2)+…+1/(3n+1)>1(n∈N+)时,S1等于这道题把我弄得很纠结,

Question

用数学归纳法证明Sn=1/(n+1)+1/(n+2)+…+1/(3n+1)>1(n∈N+)时,S1等于
这道题把我弄得很纠结,

Answer 1

证明：当n=1时,1/2 + 1/3 +1/4=13/12＞1,结论成立.假设当n=k时结论成立,即Sk=1/(k+1)+1/(k+2)+…+1/(3k+1)>1我们来证明n=k+1时,结论也成立（我们会证明S(k+1)＞Sk）因为S(k+1)=1/(k+2)+1/(k+3)+…+1/(3k+4)=[1/(k+1)...