f(n)=(1/n+1)+(1/n+2)+.+(1/n+3),则f(k+1)=最后一项是1/3n+1 .看错了- -

问题描述:

f(n)=(1/n+1)+(1/n+2)+.+(1/n+3),则f(k+1)=
最后一项是1/3n+1 .看错了- -