(4x2n−2y4−6xnyn+3+9x2y2n+2)(2xn−1y2+3xyn+1)=(4x2n−2y4−6xnyn+3+9x2y2n+2)(2xn−1y2)+(4x2n−2y4−6xnyn+3+9x2y2n+2)(3xyn+1)=4x2n−2y42xn−1y2−6xnyn+32xn−1y2+9x2y2n+22xn−1y2+4x2n−2y43xyn+1−6xnyn+33xyn+1+9x2y2n+23xyn+1=8x3n−3y6−12x2n−1yn+5+18xn+1y2n+4+12x2n−1yn+5−18xn+1y2n+4+27x3y3n+3=8x3n−3y6+27x3y3n+3=y3(8x3n−3y3+27x3y3n)
(4x2n−2y4−6xnyn+3+9x2y2n+2)(2xn−1y2+3xyn+1)=(4x2n−2y4−6xnyn+3+9x2y2n+2)(2xn−1y2)+(4x2n−2y4−6xnyn+3+9x2y2n+2)(3xyn+1)=4x2n−2y42xn−1y2−6xnyn+32xn−1y2+9x2y2n+22xn−1y2+4x2n−2y43xyn+1−6xnyn+33xyn+1+9x2y2n+23xyn+1=8x3n−3y6−12x2n−1yn+5+18xn+1y2n+4+12x2n−1yn+5−18xn+1y2n+4+27x3y3n+3=8x3n−3y6+27x3y3n+3=y3(8x3n−3y3+27x3y3n)