等差数列前n项立方和公式 等差数列前n项立方和公式有哪些

1．a(n)=a(1)+(n-1)d

2．[a(n)]^3=[a(1)+(n-1)d]^3=[a(1)]^3+3(n-1)d[a(1)]^2+3(n-1)^2d^2 a(1)+(n-1)^3d^3

3．[a[1]]^3+a[2]^3+...........+a[n]^3

4．=n[a(1)]^3

5．+3d[a(1)]^2 [0+1+2+.......(n-1)]

6．+3d^2 a(1) [0^2+1^2+...........+(n-1)^2]

7．+d^3 [0^3+1^3+........+(n-1)^3]

8．=n[a(1)]^3+3d[a[1]]^2 n(n-1)/2+ n[a(1)]^3*(n-1)n(2n-1)/2+d^3*n^2(n-1)^2/4