一道奥数题目

：1/1*5+1/2*6+1/3*7+1/4*8+1/5*9..............+1/48*52
=1/4[1-1/5]+1/4[1/2-1/6]+1/4[1/3-1/7]+1/4[1/4-1/8]+1/4[1/5-1/9]+...+1/4[1/48-1/52]
=1/4[1-1/5+1/2-1/6+1/3-1/7+1/4-1/8+1/5-1/9+...+1/48-1/52]
=1/4[1+(1/2+1/3+1/4+...+1/48)-(1/5+1/6+1/7+...+1/52)]
=1/4[1+(1/2+1/3+1/4)-(1/49+1/50+1/51+1/52)]
=1/4[1+13/12-(99/2450+103/2652)]
=1/4*2.08176
=0.520440945

大哥。题目呢。。。？

题目呢。。。？

题目很简单啊,你把1/1*5分解成1/4 *(1/1-1/5) ,1/2*6分解成1/4 *(1/2-1/6),依次分解.最后合并展开.你就知道答案了