简便计算:1/2+1/6+1/12+1/201/30+1/42+1/56
问题描述:
简便计算:1/2+1/6+1/12+1/201/30+1/42+1/56
答
=1/1*2+1/2*3+.1/7*8
=1/1-1/2+1/2-1/3+.1/7-1/8
消去中间项
=1-1/8=7/8