(1²+3²+…+99²)-(2²+4²+…+100²)=?
问题描述:
(1²+3²+…+99²)-(2²+4²+…+100²)=?
答
(1²+3²+…+99²)-(2²+4²+…+100²)
=(1+2)×(1-2)+(3+4)×(3-4)+……+(99+100)×(99-100)
=(1+2+3+4+……+99+100)×(-1)
=-(1+100)×100/2
=-5050