100²-99²+98²-97²+96²-95²+……+2²-1²
=(100-99)(100+99)+(98-97)(98+97)+(96-95)(96+95)+……+(2-1)(2+1)
=100+99+98+97+96+.+2+1
=(100+1)*100/2
=5050
100²-99²+98²-97²+96²-95²+……+2²-1²
=(100-99)(100+99)+(98-97)(98+97)+(96-95)(96+95)+……+(2-1)(2+1)
=100+99+98+97+96+.+2+1
=(100+1)*100/2
=5050