Sn=2n/n+1 ,Sn=1+1/1+2+1/1+2+3+...1/1+2+3..n这个数学归纳法当n=k+1时,Sk+1=(2k/k+1) + (1/1+2+3...
问题描述：
Sn=2n/n+1 ,Sn=1+1/1+2+1/1+2+3+...1/1+2+3..n这个数学归纳法当n=k+1时,Sk+1=(2k/k+1) + (1/1+2+3...
答
分母=(n+1)*n/21/((n+1)*n/2)=2/(n+1)n=2/n-2/(n+1) Sn从第2项开始单数项和后一双数项可约sn=2/1-2/(n+1)=2n/(n+1)数学归纳法Sk+1=2k/(k+1)+1/(1+2+...+k+k+1)=2k/(k+1)+2/(k+1)-2/(k+2)=2(k+1)/(k+2)=2(k+1)/((k+1)...