a) 3x-x = 0 => 2x = 0 => x = 0
б) 3x-3x = 4 => 0 = 4 => нет корней
в) x^2 + x - 6 = 0 => D = 1 + 24 = 25 => x = (-1 +- 5)/2 => x1 = 2, x2 = -3
г) x^2 + 4x +3 = 0 => D = 16 - 12 = 4 => x = (-4 +- 2)/2 => x1 = -1, x2 = -3
д) x^2 - 4x = 0 => x(x-4) = 0 => x1 = 0, x2 = 4
е) x^3 + 2 - 3x = 0 => (x-1)*(x^2 + x - 2) = 0 => x1 = 1, x^2 + x - 2 = 0 => x2 = x1 = 1, x3 = -2