1) (9у-а^4)(9y+a^4)
2) (4xy^2-9z)(4xy^2+9z)
3) (5m-7n)(5m+7m)
4) (0,7p^2-mq^3)(0,7p^2+mq^3)
5) (1-8a^4)(1+8a^4)
6) a^4(1-a^4) = a^4(1-a)(1+a)(1+a^2)
7) (16m^4n^6-9p^4)/144 = ((4m^2n^3-3p^2)(4m^2n^3+3p^2))/12^2 (144)
8) (64a^2x^4-225y^4)/400 = ((8ax^2-15y^2)(8ax^2+15y^2))/20^2 (200)
Как то так...