因为n是正整数,1^n=1(-1)^n·(-1)^n+1= [(-1)(-1)]^n+1=1^n+1=1+1=2
(-1)^n (-1)^n + 1 = 1 + (-1)^(2 n) = 2哭啊,,,虽然回答早了,可惜最后一步竟然错了,,,唉~~~
(-1)^n (-1)^n + 1 = 1 + 2(-1)^ n当n为单数时1 + 2(-1)^ n=-1当n为双数时1 + 2(-1)^ n=31)^n (-1)^n + 1 = 1 + (-1)^(2 n) = 1