12) (a)4 = a24 a2n

12) $$\frac{(a^9)^4}{a^{2n}} = a^{24}$$ $$\frac{a^{36}}{a^{2n}} = a^{24}$$ $$a^{36-2n} = a^{24}$$ Следовательно, $$36 - 2n = 24$$ $$-2n = 24 - 36$$ $$-2n = -12$$ $$2n = 12$$ $$n = 12 : 2$$ $$n = 6$$

Ответ: 6