2) $$-0,4x^5 \cdot (2x^3)^4$$

$$-0,4x^5 \cdot (2x^3)^4 = -0,4x^5 \cdot 16x^{12} = -0,4 \cdot 16 \cdot x^5 \cdot x^{12} = -6,4x^{5+12} = -6,4x^{17}$$

Ответ: $$-6,4x^{17}$$