Question

100*100-99*99+98*98-97*97+96*96-95*95+.+2*2-1*1=?求详解

Answer 1

100*100-99*99+98*98-97*97+96*96-95*95+.+2*2-1*1

=(100+99)(100-99)+(98+97)(98-97)+(96+95)(96-95)+.+(2+1)(2-1)

=100+99+98+97+96+95+.+1

=100(100+1)/2

=5050