先化简再求值:(a^2+2a+1)/(a^3-a)-2/(a-1)=(a+1)^2/[a(a+1)(a-1)-2/(a-1)=(a+1)/[a(a-1)]-2/(a-1)=[(a+1)-2a]/[[a(a-1)]=(1-a)/[a(-1)]=-1/a=-1/(根3-根2)=-(根3+根2)/[(根3+根2)(根3-根2)=-根3-根2