№3. 0.2y (5y^2 - 1) (2y^2 + 1) = (y^3 - 0.2y) (2y^2 + 1) = 2y^5 + y^3 - 0.4y^3 - 0.2y = 2y^5 + 0.6y^3 - 0.2y.
№4. а) 3x - xy - 3y + y^2 = x (3 - y) - y (3 - y) = (3 - y) ( x - y);
б) ax - ay + cy - cx - x + y = x (a - c - 1) - y (a - c - 1) = (a - c - 1) (x - y).
Надеюсь
Объяснение:
