1. c⁹ ⋅ c². 2. b⁸ : b⁴. 3. (a⁵)³. 4. (xy)ⁿ. 5. (b/c)³.

Решение:

1. \( c^9 \cdot c^2 = c^{9+2} = c^{11} \)
2. \( b^8 : b^4 = b^{8-4} = b^4 \)
3. \( (a^5)^3 = a^{5 \times 3} = a^{15} \)
4. \( (xy)^n = x^n y^n \)
5. \( \left(\frac{b}{c}\right)^3 = \frac{b^3}{c^3} \)

Ответ: 1. \( c^{11} \); 2. \( b^4 \); 3. \( a^{15} \); 4. \( x^n y^n \); 5. \( \frac{b^3}{c^3} \).