1*2+2*3+3*4+4*5+5*6+......+99*100=???

2025-03-01 00:20:29
推荐回答(2个)
回答1:

(1^2+1)+(2^2+2)+....+(99^2+99)
= 1^2+2^2+....+99^2+(1+2+...+99)
= 99*(99+1)(2*99+1)/6+(1+99)*99/2
= 328350+4950
= 333300

回答2:

=55*99*10^13