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++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