第1个回答 2013-04-10
设s = 1 + X + X(X +1)+ X(X +1)^ 2 + ... + X(X +1)^ N
(X +1)=(1 + X)^ 2 + X(X +1)^ 2 + X(X +1)^ 3 + ... + X(X +1)^ n +1个
(X +1)SS = X(X +1)^ N +1 +(1 + X)^ 2 - [1 + X + X(X + 1)],
XS = X(X +1)^(N +1)
=(X +1)^(N +1)
1 + X + X(X + 1)+ X(X +1)^ 2 + ... + X(X + 1)^ N =(X +1)^(N +1)