请用放缩法证明:1+1/根号2+1/根号3+------+1/根号n<2根号n

问题描述:

请用放缩法证明:1+1/根号2+1/根号3+------+1/根号n<2根号n

证明:原式=1+2/(√2+√2)+2/(√3+√3)+2/(√4+√4)+...2/(√n+√n)