三分之一加十五分之十三加三十五之三十三加六十三分之六十一

更新时间2018-09-19 06:14:53

原式=1/3+13/15+33/35+61/63

      =(5/15+13/15)+(297/315+305/315)

      =6/5+602/315

      =378/315+602/315

      =196/63

      =28/9

(1×3-2)/(1×3)+(3×5-2)/(3×5)+(5×7-2)/(5×7)+(7×9-2)/(7×9)

=1-2/(1×3)+1-2/(3×5)+1-2/(5×7)+1-2/(7×9)

=4-(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9)

=4-(1-1/9)

=4-(8/9)

=3又1/9