因为x=2
所以将代数式展开可以得[(64x^3y-9xy^3)-y/4(16x-9y)]*8x
=2^9x^4y-2^3*9x^2y^3-2xy(16x-9y)
=2^13y-2^5*9y^3-2^7y+2^2*9y^2
=-288y^3+36y^2+3968y