根据题意,lim(bn+1)/(bn)=根号3,lim(an+1)/(an)=根号3/5,那lim(bn+1²/an+1²)/(bn²/an²)=[(bn+1)/(bn)]²×[(an)/(an+1)]²=3·5/3=5,注：最上面两个表达式求得不是收敛半径,是收敛半径...最终求得的不是ρ吗，ρ的倒数才是R啊