1) (x-4)(x+4)
2) (0.7-y)(0.7+y)
3) (y-0.3)(y+0.3)
4) (4m-3)(4m+3)
5) (12-9y)(12+9y)
6) (25t-11a)(25t+11a)
7) (xy-0.7b)(xy+0.7b)
8) (4/5b^2-1/7a^4)(4/5b^2+1/7A^4)
9) (3a^2b^4-9c^3)(3a^2b^4+9c^3)
10) (5a-3b-25a)(5a+3b-25a)=(-30a-3b)(-20a+3b)
a^4(это степень)