1又1/2＋3又1/4＋5又1/8＋···＋[(2n-1)+1/2的n次方]=
问题描述：
1又1/2＋3又1/4＋5又1/8＋···＋[(2n-1)+1/2的n次方]=
答
=[1+3+……+(2n-1)]+(1/2+1/4+……+1/2^n)
=[1+(2n-1)]*n/2+1/2*(1-1/2^n)/(1-1/2)
=n²+1-1/2^n