计算:1/2+1/6+1/20+1/30+1/42+1/56+1/72.最好是简便的算法!
问题描述:
计算:1/2+1/6+1/20+1/30+1/42+1/56+1/72.最好是简便的算法!
答
1/2+1/6+1/20+1/30+1/42+1/56+1/72
=1/2+(1/2-1/3)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)+(1/7-1/8)+(1/8-1/9)
=1-1/3+1/4-1/9
=29/36