原式=1/2+1/4+1/8=1/16+1/32+……+1/1024+2048 !=是+吧
=3/4+1/8+1/16+1/32+……+1/1024+2048
=7/8+1/16+1/32+……+1/1024+2048
找到规律：1/2^1+1/2^2+1/2^3
=2^2-1/2^2+3
=2^3-1/2^2
=7/8+1/16+1/32+……+1/1024+2048
=1023/1024+2048
=2048又1023/1024=是+没错我怀疑题目有误注意看题！