因为2/(1×3)=1- 1/3 2/(3×5)=1/3 -1/52/(5×7)=1/5 -1/7……以此类推2/(2015×2017)=1/2015 - 1/2017所以这题=1- 1/3 +1/3 -1/5 +1/5 -1/7 +……+1/2015 -1/2017=1- 1/2017=2016/2017
