18) -0.2x(-3x^2+2x-7) =

$$-0.2x(-3x^2+2x-7) = -0.2x \cdot (-3x^2) -0.2x \cdot 2x -0.2x \cdot (-7) = 0.6x^3 - 0.4x^2 + 1.4x$$ Ответ: $$0.6x^3 - 0.4x^2 + 1.4x$$