(1/2)(a2+a3)=(0,1/2,1,3/2)^TA[(1/2)(a2+a3)-a1]=0(0,1/2,1,3/2) - (1,2,3,4) = (-1,-3/2,-2,-5/4)哪里错了?答案是(2,3,4,5)^T