а) 2c(1+c) - (c-2)(c+4) = 2c + 2c^2 - (c^2 + 2c - 4c - 8) = 2c + 2c^2 - c^2 - 2c + 4c + 8 = 2c^2 + c + 8.
б) (y+2)^2 - 2y(y+2) = y^2 + 4y + 4 - 2y^2 - 4y = -y^2.
в) 30x + 3(x-5)^2 = 30x + 3(x^2 - 10x + 25) = 30x + 3x^2 - 30x + 75 = 3x^2 + 75.
а) 2c(1+c) - (c-2)(c+4) = 2c + 2c^2 - (c^2 + 2c - 4c - 8) = 2c + 2c^2 - c^2 - 2c + 4c + 8 = 2c^2 + c + 8.
б) (y+2)^2 - 2y(y+2) = y^2 + 4y + 4 - 2y^2 - 4y = -y^2.
в) 30x + 3(x-5)^2 = 30x + 3(x^2 - 10x + 25) = 30x + 3x^2 - 30x + 75 = 3x^2 + 75.