原式=(a-1)^(2n-1)+2(1-a)^2n+(a-1)^(2n+1)=(a-1)^(2n-1)+2(a-1)^2n+(a-1)^(2n+1)=(a-1)^(2n-1)[1+2(a-1)+(a-1)^2]=(a-1)^(2n-1)(1+a-1)^2=(a-1)^(2n-1)a^2手机提问的朋友在客户端右上角评价点【满意】即可....