4а²-12аb+5b²=(2a-3b)²-4b²=(2a-3b)²-(2b)²=(2a-3b+2b)(2a-3b-2b)=(2a-b)(2a-5b)
9c²-24cd+7d²=(3c-4d)²-9d²=(3c-4d)²-(3d)²=(3c-4d+3d)(3c-4d-3d)=
=(3c-d)(3c-7d)
25a²-20ab-12b²=(5a-2b)²-16b²=(5a-2b)²-(4b)²=(5a-2b-4b)(5a-2b+4b)=
=(5a-6b)(5a+2b)
9m²-30mk+16k²=(3m-5k)²-9k²=(3m-5k)²-(3k)²=(3m-5k-3k)(3m-5k+3k)=
=(3m-8k)(3m-2k)