По (x-4b)*(x^2+4x*b+16b^2)+64b^3+x^3+b^2

 (x-4b)*(x^2+4x*b+16b^2)+64b^3+x^3+b^2=(x-4b)(x²+x(4b)+(4b)²)+64b³+x³+b²=x³-(4b)³+64b³+x²+b²=x³-64b³+64b³+x²+x³=2x³+x²=x²(2x+1)