a) $$(4xy)^2 = 4^2 \cdot x^2 \cdot y^2 = 16x^2y^2$$;
б) $$(8a^2b)^2 = 8^2 \cdot (a^2)^2 \cdot b^2 = 64a^{2\cdot2}b^2 = 64a^4b^2$$;
в) $$(-xy^2z^3)^5 = (-1)^5 \cdot x^5 \cdot (y^2)^5 \cdot (z^3)^5 = -x^5y^{2\cdot5}z^{3\cdot5} = -x^5y^{10}z^{15}$$;
г) $$\left(\frac{1}{2}ab^2\right)^3 = \left(\frac{1}{2}\right)^3 \cdot a^3 \cdot (b^2)^3 = \frac{1^3}{2^3}a^3b^{2\cdot3} = \frac{1}{8}a^3b^6$$.