5又2/9+5又2/99+5又2/999+5又2/9999+5又2/99999，用简便方法怎么做，答案是多少？

日期：2012-08-05 21:32:07 人气：1

5又2/9+5又2/99+5又2/999+5又2/9999+5又2/99999 =5x5+2/9+2/99+2/999+2/9999+2/99999 =25+2/9(1+1/11+1/111+1/1111+1/11111) =25+2/9x(1370219631/1370219631+124565421/1370219631+12344321/137