23) (20xy²+5x²y-4xy)⋅(-2x²y) =

23) (20xy²+5x²y-4xy)⋅(-2x²y) =

Раскроем скобки:

$$20xy^2 \cdot (-2x^2y) = -40x^3y^3$$

$$5x^2y \cdot (-2x^2y) = -10x^4y^2$$

$$(-4xy) \cdot (-2x^2y) = 8x^3y^2$$

Получаем:

$$-40x^3y^3 - 10x^4y^2 + 8x^3y^2$$

Ответ: $$-40x^3y^3 - 10x^4y^2 + 8x^3y^2$$