因为1/2 =1- 1/2
1/4=1/2- 1/4
‘’‘’‘’‘’
1/128=1/64-1/128
故原式可整理为1- 1/128 =127/128
求采纳
1/2+1/4+1/8+1/16+1/32+1/64+1/128
=1/128x64+1/128x32+1/128x16+1/128x8+1/128x4+1/128x2+1/128
=1/128x(64+32+16+8+4+2+1)
=1/128x127
=127/128
=1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/128-1/128=1/2+1/4+1/8+1/16+1/32+1/64+1/64-1/128=
1/2+1/4+1/8+1/16+1/32+1/32-1/128=1/2+1/4+1/8+1/16+1/16-1/128=1/2+1/4+1/8+1/8-1/128=1-1/128=127/128
先乘以128就是一个数列了
然后再除以128
(1+2+4+8+16+32+64)/128=127/128