(5-1)/5+(5²-1)/5²+(5³-1)/5³+.+(5的n次方-1)/5的N次方=?

问题描述:

(5-1)/5+(5²-1)/5²+(5³-1)/5³+.+(5的n次方-1)/5的N次方=?

n-1/4+1/4X1/5^n