因为:(n+1)³=n³+3n²+3n+1
则有: 1³=1³
2³=1³+3×1²+3×1+1
3³=2³+3×2²+3×2+1
……
n³=(n-1)³+3(n-1)²+3(n-1)+1
(n+1)³=n³+3n²+3n+1
上述各式相加得:(n+1)³=1³+3×(1²+2²+3²+……+n²)+3×(1+2+3+……+n)+n
3×(1²+2²+3²+……+n²)
=(n+1)³-n-1-3×(1+2+3+……+n)
=n³+3n²+2n-3/2×n(n+1)
=n³+3n²/2+n/2
=1/2×(2n³+3n²+n)
=n(2n+1)(n+1)/2
所以:1²+2²+3²+……+n²=n(2n+1)(n+1)/6