А)
(х-4)²-9х²=(х-4)²-(3х)²=(х-4-3х)(х-4+3х)=(-2х-4)(4х-4)
б)
(2х-у)²-(х+3у)²=(2х-у-(х+3у))(2х-у+х+3у)=(2х-у-х-3у)(3х+2у)=
=(х-4у)(3х+2у)
в)
144-(а+9)²=12²-(а+9)²=(12-(а+9))(12+а+9)=(12-а-9)(21+а)=
=(3-а)(21+а)
г)
(z+1)²-(2z-3)²=(z+1-(2z-3))(z+1+2z-3)=(z+1-2z+3)(3z-2)=
=(-z+4)(3z-2)