求和:1+3/4+4/8+……+n/2^n-1+n+1/2^n
求和:1+3/4+4/8+……+n/2^n-1+n+1/2^n
若n为正整数,求1/n(n+1)+1/(n+1)(n+2)+1/(n+2)(n+3)+1/(n+3)(n+4)+.+1/
求和4^n+3×4^(n-1)+3^2×4(n-2)+……+3^(n-1)×4+3^n
一道数列求和题1/2n+3/4n+5/8n+...+(2n-1)/n*2^n
求和:1×1/2+3×1/4+5×1/8+…+〔(2n-1)+1/2^n〕
求和sn=1×2×3+2×3×4+……+n(n+1)(n+2)
1*2*3+2*3*4+……+n(n+1)(n+2) 求和
求和:Sn=1*2*3+2*3*4+……+n(n+1)(n+2)
n分之1+n分之2+n分之3+……n分之n-1=
n(n+1)(n+2)数列求和
求和:Sn=1*n+2*(n-1)+3*(n-2)+……+n*1
化简整式.六分之一× [ 3n×(n+1)+2n×(n+1)×(n-1)]