Ответ:

\[-2\frac14=-\frac94,\qquad \left(-\frac13a^3b\right)^2=\frac19a^6b^2.\]

\[\frac19a^6b^2\cdot\left(-\frac94a^2b^3\right)=-\frac{9}{36}a^8b^5=-\frac14a^8b^5.\]

Ответ: \(-\frac14a^8b^5\).