(1/n^3)*（n∑,i=1）(i^3)为什么等于 1/n^3*[n*(n+1)(2n+1)]/6

(1/n^3)*（n∑,i=1）(i^3)为什么等于 1/n^3*[n*(n+1)(2n+1)]/6 n属于r 求1+i^n+i^2n+i^3n 计算:1+i+i^2+i^3+...+i^n i^4n=1,i^(4n+1)=i,i^(4n+2)=-1,i^(4n+3)=-i,当n∈Z时,能成立吗,书上是n∈N (1+3i)^n=(√3-i)^n成立的最小正整数n 高二文科复数运算!i^4n+i^4n+1+i^4n+2+i^4n+3 编程计算：n ∑(i+1)/i!i=1（精度要求为(n+1)/n! 天才们……找规律,求abc……xyz及M若i为从1到n的正整数则∑i^1=1+2+3+.n=n(n+1)/2∑i^2=1^2+2^2+3^2+.n^2=n(n+1)(n+2)/3-∑i^1=n(n+1)(2n+1)/6∑i^3=1^2+2^3+3^3+.n^3= n(n+1)(n+2) (n+3)/4-3∑i^2-2∑i^1= n^2 (n+1) ^2/4∑i^4=(n+4)!/(5* 组合数学中恒等式的证明：1、Σ(i=0,n)i^2*C(n,i)=n*(n+1)*2^(n-2);还有一个：Σ(i=0,n)(1/(i+1)(i+2))C(n,i)=(2^(n+2)-n-3)/((n+1)(n+2))麻烦给出详解, 关于lingo程序的,sets:A/1..4/:c,b,n;X/A,A/:D;endsetsmin=1.1*n(1)+1.2*n(2)+1.3*n(3)+1.4*n(4);@for(A(i):@sum(A(j):c(i)*D(i,j)=1750);@for(A(i):@sum(A(j):n(i)*D(i,j)=b(i));@for(A(i):@gin(n(i)));@for(A(j):@for(A(i):@gin(D(i,j))));n(1)>n(2);n(2)>n(3);n 设S=1+2i+3i+.+(4n+1)i的4n次方（n属于N）,则S=?S=1+2i+3的i的平方+....+(4n+1)i的4n次方（n属于N），则S=？ 求n项和数列极限,通式为i/(i+n)就是n->无穷,1/(n+1)+2/(n+2)+3/(n+3)+...+n/2n; #define N 20 fun(int a[],int n,int m) {int i; for(i=m;i>n;i--)a[i+1]=a[i]; return m; } void main() #define N 20fun(int a[],int n,int m){int i;for(i=m;i>n;i--)a[i+1]=a[i];return m;}void main(){ int i,a[N]={1,2,3,4,5,6,7,8,9,10};fun(a,0,N/2);for(i=0;i Dim i As Integer,n As Integer For i = 0 To 50 i = i + 3 n = n + 1 If i > 10 Then Exit For Next PriDim i As Integer,n As IntegerFor i = 0 To 50i = i + 3n = n + 1If i > 10 Then Exit ForNextPrint n怎么算 1+i^n+i^2n+...+i^2000n＝? 分母是等差数列,分子是等比数列,求和Sn=1/（1+i）^2+2/(1+i)^3+3/(1+i)^4+.+(n-1)/(1+i)^n A=12*n*a*i(1+i)^(12*n)/((1+i)^(12*n)-1);B=a+2*i*((6*n*a-(3*n-1)(12*n-1));当1 (i?a[i-1]!=' ':1)