A) 0.16a^4 - 0.09b^2 = (0.4a^2 - 0.3b)*(0.4a^2 + 0.3b)
б) 5x^2 + 20x + 20 = 5(x + 2)^2
в) 81c^4 + 3b^3c = 3c * (27c^3 + b^3) = 3c * (3c + b) * (9c^2 - 3cb + b^2)
а) a^2 - 9b^2 - a - 3b = (a + 3b)(a - 3b) - (a + 3b) = (a + 3b)*(a - 3b -1)
б) 25c^2 - 4x^2 - 4x - 1 = 25c^2 - (2x + 1)^2 = (5c + 2x + 1) * (5c - 2x - 1)
в) 27a^3 - 8 = (3a - 2)(9a^2 + 6a + 4)