原式=(100+99)(100-99)+(98+97)(98-97)+......+(2+1)(2-1) =100+99+98+97+......+3 =5050-3 =5047
(100x100-99x99)+(98x98-97x97)+……+(2x2-1x1)=(100+99)+(98+97)+……+(2+1)=100+99+98+91+……+2+1=5050