2. Сократите дробь: 1) \(\frac{10m^8n^8}{15m^4n^4}\); 2) \(\frac{14xy-21y}{7xy}\); 3) \(\frac{m^2-9}{2m+6}\); 4) \(\frac{a^2-12a+36}{36-a^2}\).

1. \(\frac{10m^8n^8}{15m^4n^4}=\frac{2m^4n^4}{3}\).
2. \(\frac{14xy-21y}{7xy}=\frac{7y(2x-3)}{7xy}=\frac{2x-3}{x}\).
3. \(\frac{m^2-9}{2m+6}=\frac{(m-3)(m+3)}{2(m+3)}=\frac{m-3}{2}\).
4. \(\frac{a^2-12a+36}{36-a^2}=\frac{(a-6)^2}{(6-a)(6+a)}=\frac{(a-6)^2}{-(a-6)(a+6)}=-\frac{a-6}{a+6}=\frac{6-a}{a+6}\).

Ограничения: в 1) \(m\ne0\), \(n\ne0\); в 2) \(x\ne0\), \(y\ne0\); в 3) \(m\ne-3\); в 4) \(a\ne\pm6\).

Ответ: 1) \(\frac{2m^4n^4}{3}\); 2) \(\frac{2x-3}{x}\); 3) \(\frac{m-3}{2}\); 4) \(\frac{6-a}{a+6}\).