Выполните действие: а) 10 х^2 - (4 х-1) (1+4 х) б) - (7 а+2) (2-7 а) + 4 в) (3m-k) (3m+k) - 2m (5m-k) г) 5d (4c+5d) - (2c+5d) (5d-2c)

а) 10 х^2 - (4 х - 1) (1 + 4 х) = 10x^2 - (16x^2 - 1) = 10x^2 - 16x^2 + 1 = 1 - 6x^2.

б) - (7 а + 2) (2 - 7 а) + 4 = 4 - (7a * 7a - 2 * 2) = 4 - (49a^2 - 4) = 4 - 49a^2 + 4 = 8 - 49a^2.

в) (3m - k) (3m + k) - 2m (5m - k) = (3m * 3m - k * k) - 2m * 5m + 2m * k =

9m^2 - k^2 - 10m^2 + 2mk = 2mk - m^2 - k^2.

г) 5d (4c + 5d) - (2c + 5d) (5d - 2c) = 5d * 4c + 5d * 5d - (5d * 5d - 2c * 2c) =

20dc + 25d^2 - (25d^2 - 4c^2) = 20dc + 25d^2 - 25d^2 + 4c^2 = 20dc + 4c^2.