\[\begin{aligned} \frac{(x^2)^3}{2a^3} \cdot \frac{(4a^4)^2}{x^3} &= \frac{x^6}{2a^3} \cdot \frac{16a^8}{x^3} \\ &= \frac{16x^6a^8}{2a^3x^3} \\ &= 8x^3a^5 \end{aligned}\]
\[\begin{aligned} 8x^3a^5 &= 8 \cdot (-0.31)^3 \cdot (\frac{1}{13})^5 \\ &= 8 \cdot (-0.029791) \cdot (\frac{1}{37129371}) \\ &= \frac{-0.238328}{37129371} \end{aligned}\]
Ответ: -0.238328 / 37129371