1 1 3 1 1 3 1 1 3 1 1 3 1 1 3 1 1 3 1 1
多项式(a—2)(a^2+2a+4)—[3a(a+1)^2-2a(a-1)^2-(3a+1)(3a-1)]+a(1+a)的值与a的取值无关
