(x-1/6y)(2x+1/3y)(3x^2+1/12y^2)=（2x²-1/3xy+1/3xy-1/18y²)(3x²+1/12y²)=（2x²-1/18y²)(3x²+1/12y²)=6x⁴-1/6x²y²+1/6x²y²-1/216y⁴=6x&#...