а) (c - 2)(c + 3) - c^2 = c^2 + 3c - 2c - 6 - c^2 = c
б) 7(x + 8) + (x + 8)(x - 8) = 7x + 56 + x^2 - 8^2 = x^2 + 7x + 56 - 64 = x^2 + 7x - 8
в) (x + 5)4x - (2x + 5)^2 = 4x^2 + 20x - 4x^2 - 20x - 25 = -25
а) (c - 2)(c + 3) - c^2 = c^2 + 3c - 2c - 6 - c^2 = c
б) 7(x + 8) + (x + 8)(x - 8) = 7x + 56 + x^2 - 8^2 = x^2 + 7x + 56 - 64 = x^2 + 7x - 8
в) (x + 5)4x - (2x + 5)^2 = 4x^2 + 20x - 4x^2 - 20x - 25 = -25