(1/4х^2-16/y^2)*2xy/8x-y
Y^2-64*2xy//4x^2y^2*8x-y=(y-8x)(y+8x)*2xy//4x^2y^2*8x-y=-(y-8x)(y+8x)*2xy//(y-8x)*4x^2y^2 = - y+8x/xy