Найдите значение выражения: а) $$rac{3^{27}}{9^{12}}$$; б) $$rac{125^{11}}{25^{17}}$$; в) $$rac{(a+2)^2}{3a+6}$$; г) $$rac{a^2-1}{a^2-2a+1}$$

a) $$rac{3^{27}}{9^{12}} = rac{3^{27}}{(3^2)^{12}} = rac{3^{27}}{3^{24}} = 3^{27-24} = 3^3 = 27$$

б) $$rac{125^{11}}{25^{17}} = rac{(5^3)^{11}}{(5^2)^{17}} = rac{5^{33}}{5^{34}} = 5^{33-34} = 5^{-1} = rac{1}{5}$$

в) $$rac{(a+2)^2}{3a+6} = rac{(a+2)^2}{3(a+2)} = rac{a+2}{3}$$

г) $$rac{a^2-1}{a^2-2a+1} = rac{(a-1)(a+1)}{(a-1)^2} = rac{a+1}{a-1}$$