解(a-b)(a+b)(a-b)²(b-a)³(a+b)²=-(a+b)³(a-b)(a-b)²(a-b)³=-(a+b)³(a-b)^61/2m×mn×m-m×n×m^2+1/2m^2×n×m=1/2nm^3-nm^3+1/2nm^3=(1/2-1+1/2)nm^3=0×nm^3=0