Ответ:

  1. \(3a^2-12=3(a^2-4)=3(a-2)(a+2)\).

  2. \(64a-a^3=a(64-a^2)=a(8-a)(8+a)\).

  3. \(c^3-\frac{25}{36}cd^2=c\left(c^2-\frac{25}{36}d^2\right)=\frac{c}{36}(6c-5d)(6c+5d)\).