4×5+5×6+6×7+……+35×36+36×37
问题描述:
4×5+5×6+6×7+……+35×36+36×37
答
=(4^2+4)+(5^2+5)+...+(36^2+36)
=(1^2+2^2+...36^2)-(1+4+9)+(4+36)*(36-4+1)/2
=(2*36+1)(36+1)*36/6-14+660
=16852