-2a^3b+8a²b²-8ab^3=-2ab(a^2-4ab+4b^2)=-2ab(a-2b)^2(7x²+2y²)²-(2x²+7y²)²=[ (7x²+2y²)-(2x²+7y²)][ (7x²+2y²)+(2x²+7y²)]=(7x...