Question

1+n的1次方+n的2次方+n的3次方=0

Answer 1

1+n+n^2+n^3=0

1+n+n^2(1+n)=0

(1+n)(1+n^2)=0解得n=-1

则1+n+n^2+n^3+...+n^1999+n^2000

=1-1+1-1+...-1+1

=1(因为该式有2001项,后面项全消掉了)