因式分解?这可是前n项非0自然数的平方求和呀,结果为：(2n+1)(n+1)n/6 求法为：(n+1)^3 = n^3 + 3n^2 + 3n + 1(n+1)^3 - n^3 = 3n^2 + 3n + 1两边从1..n求和(n+1)^3 -1 = 3S(n^2) + 3S(n) + nS(n) = n*(n+1)/2 等差数...