1+1\2+3\4+7\8+15\16+31\32+63\64+127\128
问题描述:
1+1\2+3\4+7\8+15\16+31\32+63\64+127\128
答
1+1\2+3\4+7\8+15\16+31\32+63\64+127\128
=1×8-(1/2+1/4+1/8+...+1/128)
=8-1/2(1-(1/2)^7)/(1-1/2)
=8-1+(1/2)^7
=7+(1/2)^7
=7又1/128