Решим данное задание:
$$ (5y^2 + 5x^2 + 5xy) \cdot (y^2 - x^2 - xy - 1) $$
$$ = 5(y^2 + x^2 + xy) \cdot (y^2 - x^2 - xy - 1) $$
$$ = 5(y^4 - x^4 - x^2y^2 - y^2 + x^2y^2 - x^4 - x^3y - x^2 + xy^3 - x^3y - x^2y^2 - xy) $$
$$ = 5(y^4 - 2x^4 - x^2y^2 - y^2 - 2x^3y - x^2 + xy^3 - xy) $$
$$ = 5y^4 - 10x^4 - 5x^2y^2 - 5y^2 - 10x^3y - 5x^2 + 5xy^3 - 5xy $$
Ответ: 5y⁴-10x⁴-5x²y²-5y²-10x³y-5x²+5xy³-5xy