(x+4)^2(x-4)^2 - (2x-1)^2(2x+1)^2
= 【(x+4)(x-4)】^2 - 【(2x-1)(2x+1)】^2
= (x^2-16)^2 - (4x^2-1)^2
= x^4-32x^2+256 - (16x^4-8x^2+1)
= -15x^4-24x^2+255