упростите выражения
1)(а+8)^2-16
2)(6+b)^2-b^2
3)81-(b-9)^2
4)(7+6a)^2-84a
5)-28y+(2y+7)^2
6)(9m+1)^2-(18m-2)
7)(6t^2-8t)(4t+1)^2
8)(11x+3)^2-(66x+21x^2)
9)3m (n+2)-(m+3)^2
10)5(x+y)^2-10xy
11)4a(a-2)^2-(a-4)^2
12)(6n-0,7)(6n+0,7)+(5n+0,7)^2