a) $$(-5a^2b^3)^2 = (-5)^2 \cdot (a^2)^2 \cdot (b^3)^2 = 25a^{2 \cdot 2}b^{3 \cdot 2} = 25a^4b^6$$
б) $$(2ab^5c^2)^3 = 2^3 \cdot a^3 \cdot (b^5)^3 \cdot (c^2)^3 = 8a^3b^{5 \cdot 3}c^{2 \cdot 3} = 8a^3b^{15}c^6$$
Ответ: a) $$25a^4b^6$$, б) $$8a^3b^{15}c^6$$