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4+9+16+...+(n+1)^2的和?

题目详情
4+9+16+...+(n+1)^2的和?
▼优质解答
答案和解析
1²+2²+3²+--------+n²=n(n+1)(2n+1)/6
4+9+16+...+(n+1)²
=1²+2²+3²+--------+(n+1)²-1
=(n+1)(n+2)(2n+3)/6-1
=[(n+1)(n+2)(2n+3)-6]/6
=(2n³+9n²+11n)/6