392. 1) (1-0,3a ÷ 0,15a²). 4α; 2) (2,25x² - 1,5xy + 2,5y²) - (-2,4xy); 5 3) 1ab.(ab-1ab²-b³).

392.

1. $$ (1 - 0.3a + 0.15a^2) \cdot 4a = 4a - 1.2a^2 + 0.6a^3 $$Ответ: $$0.6a^3 - 1.2a^2 + 4a$$
2. $$ (2.25x^2 - 1.5xy + 2.5y^2) \cdot (-2.4xy) = -5.4x^3y + 3.6x^2y^2 - 6xy^3 $$Ответ: $$-5.4x^3y + 3.6x^2y^2 - 6xy^3$$
3. $$ 1\frac{1}{3}ab \cdot (\frac{3}{4}a^2b - 1\frac{1}{2}ab^2 - \frac{5}{6}b^3) = \frac{4}{3}ab \cdot (\frac{3}{4}a^2b - \frac{3}{2}ab^2 - \frac{5}{6}b^3) = a^3b^2 - 2a^2b^3 - \frac{10}{9}ab^4 $$Ответ: $$a^3b^2 - 2a^2b^3 - \frac{10}{9}ab^4$$