Sn=1/5+2/5+1/5^3+2/5^4+----+1/5^2n-1+2/5^2n 则lim（n→∞）Sn=
问题描述：
Sn=1/5+2/5+1/5^3+2/5^4+----+1/5^2n-1+2/5^2n 则lim（n→∞）Sn=
答
Sn=(1/5+1/5^3+----+1/5^2n-1)+(2/5+2/5^4+----+2/5^2n)
两括号内都为1/25等比,用等比求和公式