б) 2 1/4 c3d (-2/3 cd2)2;

б) $$2\frac{1}{4}c^3d \cdot \left(-\frac{2}{3}cd^2\right)^2 = \frac{9}{4}c^3d \cdot \frac{4}{9}c^2d^4 = \frac{9}{4} \cdot \frac{4}{9} \cdot c^3 \cdot c^2 \cdot d \cdot d^4 = c^{3+2}d^{1+4} = c^5d^5$$.

Ответ: $$c^5 d^5$$