Question

用简便方法计算中间那个是减号.

Answer 1

解

原式

=(1²-2²)+(3²-4²)+……+(99²-100²)

=(1-2)(1+2)+(3-4)(3+4)+……+(99-100)(99+100)

=-(1+2+3+4+……+99+100)

=-(1+100)×100÷2

=-5050