Выполните умножение: 1) (4a-y)(y+4a) 2) (0,3b+х)(0,3b-x) 3) (1,1c+z)(z-1,1c) 4)

1) (4a - y)(y + 4a)  = 4ay + 16a - y - 4ay = 16a - y;

2) (0,3b + х)(0,3b - x) = 0,09b - 0,3bx + 0,3bx - x = 0,09b - x;

3) (1,1c + z)(z - 1,1c) = 1,1cz - 1,21c + z - 1,1cz = z - 1,21c;

4) (21d - k)(21d + k) = 441d + 21dk - 21dk - k = 441d - k;

5) (5a - 4b)(4b + 5a) = 20ab + 25a - 16b - 20ab = 25a - 16b;

6) (1,9c + 6d)(6d - 1,9c) = 11,4cd - 3,61c + 36d - 11,4cd =

= 36d - 3,61c